Cerium dioxide as well as preparation method and application thereof

Abstract

The invention relates to cerium dioxide and a preparation method and application thereof, and the preparation method of the sphere-like cerium dioxide comprises the following steps: (1) carrying out first mixing on cerium salt, doped metal salt, a solvent, inorganic acid and organic acid to obtain a first mixture; the doped metal salt comprises praseodymium salt and / or neodymium salt; (2) under a hydrothermal condition, carrying out second mixing on the first mixture, ammonia water and ammonium salt to obtain a second mixture with the pH value of 8-10, and carrying out sol-gel reaction to obtain sphere-like cerium dioxide sol; and (3) carrying out post-treatment on the sphere-like cerium dioxide sol to obtain the sphere-like cerium dioxide. According to the preparation method of the sphere-like cerium dioxide, provided by the invention, a mixing process and a reaction process of cerium salt and specific raw materials are designed, so that the sphere-like cerium dioxide with regular particle shape, good size uniformity and high purity and crystallinity is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of oxide preparation, and in particular to cerium dioxide and a preparation method and application thereof. Background Art

[0002] Polishing technology has important research significance in modern manufacturing, and its application range is wide, covering many fields such as aviation, aerospace, automobile, semiconductor or optics. Polishing technology can not only significantly improve the surface quality of products, but also improve the performance of materials and extend the service life. Therefore, it plays an irreplaceable role in improving product competitiveness and meeting high-end manufacturing needs.

[0003] Cerium dioxide is known as the best polishing material because of its moderate hardness and strong chemical activity, which can achieve high-precision and high-finish surface treatment. It has high polishing quality, fast efficiency and long service life. It is widely used in the polishing of TV picture tubes, eyeglass lenses, optical glass, aviation glass, integrated circuit substrates, liquid crystal displays, photomask substrates and gem products. Its excellent polishing performance enables it to play an important role in many high-precision processing fields. For example, the prior art CN116285699A discloses a high-performance rare earth polishing powder for high-generation glass, comprising the following raw materials in parts by weight: 50-80 parts of doped cerium dioxide and 10-16 parts of embedded anti-friction particles; the high-performance rare earth polishing powder is made by the following steps: adding doped cerium dioxide and embedded anti-friction particles into a stirring tank and mixing them evenly, and then crushing and grading them to control the particle size D50: 0.5-5μm, D100: 2-20μm. The obtained polishing powder is composed of doped cerium dioxide and embedded anti-friction particles, which reduces scratches on high-generation glass during polishing and reduces the generation of abrasive chips during polishing, thereby improving the utilization rate of the polishing powder while making it less likely for high-generation glass to have surface defects, thereby achieving high polishing efficiency and high polishing quality.

[0004] Although cerium dioxide has the above-mentioned advantages in the field of polishing technology, with the development of technology and processes, cerium dioxide has also shown some shortcomings. For example, cerium dioxide polishing powder is usually prepared by a crushing process, which leads to uneven particle size, which affects the polishing quality and easily causes scratches and defects on the surface of the polished workpiece; secondly, the purity of common cerium dioxide polishing powder on the market is usually between 70% and 80%, which limits its application in the field of high-precision polishing; in addition, ultrafine and nano-scale cerium dioxide polishing powders are prone to agglomeration in liquid media due to their large surface area and high surface energy, which affects the stability and polishing effect of the product.

[0005] At present, the preparation methods of cerium dioxide are usually hydrothermal method, chemical precipitation method and spray thermal decomposition method, etc. However, the purity of cerium dioxide prepared by the commonly used process methods in the prior art is low, and the product uniformity is poor, which affects the quality and polishing effect of cerium dioxide.

[0006] Therefore, how to prepare cerium dioxide particles with good product uniformity, high purity and excellent polishing effect has become a problem that needs to be solved urgently. Summary of the invention

[0007] In order to solve the above technical problems, one of the purposes of the present invention is to provide a spherical cerium dioxide and its preparation method and application. The preparation method adopted by the present invention introduces a doping metal salt into a cerium salt, and then mixes it with an inorganic acid and an organic acid. The obtained product is mixed with ammonia water and an ammonium salt under hydrothermal conditions, and the pH of the obtained mixture is subjected to a sol-gel reaction under alkaline conditions within a specific range to obtain a spherical cerium dioxide sol, and then combined with a post-treatment process to obtain spherical cerium dioxide particles, which have regular particle shape, good size uniformity, and high purity and crystallinity.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing spherical cerium dioxide, the preparation method comprising the following steps:

[0010] (1) mixing a cerium salt, a doping metal salt, a solvent, an inorganic acid and an organic acid to obtain a first mixture;

[0011] The doping metal salt includes praseodymium salt and / or neodymium salt;

[0012] (2) under hydrothermal conditions, mixing the first mixture with ammonia water and ammonium salt to obtain a second mixture, wherein the pH value of the second mixture is 8-10, and performing a sol-gel reaction to obtain a spherical cerium dioxide sol;

[0013] (3) Post-treating the quasi-spherical cerium dioxide sol to obtain the quasi-spherical cerium dioxide.

[0014] In the present invention, the pH value can be selected in the range of "8-10", such as 8, 8.2, 8.4, 8.6, 8.8, 9, 9.2, 9.4, 9.6, 9.8 or 10, etc.

[0015] The preparation method provided by the present invention is to mix cerium salt and doped metal salt with inorganic acid and organic acid in a solvent to obtain a composite cerium salt and a composite doped metal salt containing both inorganic acid radicals and organic acid radicals, and then under hydrothermal conditions, the composite cerium salt and the composite doped metal salt react with ammonia water and ammonium salt to obtain a highly active intermediate, and the pH value in the reaction solution is precisely controlled to be within the range of 8-10, and a sol-gel reaction is performed under alkaline conditions of a specific pH value, and the highly active intermediate can stably crystallize to form a specific shape of cerium dioxide seeds, and the seeds maintain a specific shape and continue to grow uniformly to form a spherical crystal nucleus with uniform size and regular morphology, and the crystal nucleus is gelled to obtain a spherical cerium dioxide sol, and the obtained sol is subjected to a post-treatment process to finally obtain a spherical cerium dioxide particle with high purity and crystallinity. The present invention also introduces a specific praseodymium salt and / or a neodymium salt as a doped metal salt in the cerium salt to promote the regulation of the morphology of the product and to improve the crystallinity of the product, thereby facilitating the polishing effect of the obtained material. The preparation method adopted by the present invention has short reaction time, simple operation and easy mass production. The prepared cerium dioxide has a quasi-spherical morphology with regular shape, uniform particles, good crystallinity and high purity. It can be widely used in semiconductor chemical mechanical polishing (CMP), high-end optical polishing or cosmetics and other fields.

[0016] Preferably, the ratio of the molar amount of cerium ions in the cerium salt in step (1) to the total molar amount of doped metal ions in the doped metal salt is (100-5000):1, for example, 100:1, 500:1, 1000:1, 1500:1, 2000:1, 2500:1, 3000:1, 3500:1, 4000:1, 4500:1 or 5000:1, etc.

[0017] In the present invention, if the molar ratio of cerium ions in the cerium salt to the doped metal ions in the doped metal salt is too low, and the cerium ion content is too low, the particles cannot be formed and spherical cerium dioxide with excellent performance cannot be obtained; if the molar ratio of the two is too high and the doped metal ion content is too low, the morphology of cerium dioxide will be affected and the crystallinity of the obtained product will be deteriorated.

[0018] Preferably, the doping metal salt in step (1) comprises praseodymium salt and neodymium salt.

[0019] Preferably, when the doped metal salt includes praseodymium salt and neodymium salt, the molar ratio of praseodymium ions in the praseodymium salt to neodymium ions in the neodymium salt is (1-10):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc.

[0020] Preferably, the cerium salt in step (1) includes any one of Ce2(CO3)3, Ce(NO3)3, CeCl3 or Ce2(SO4)3, or a combination of at least two thereof.

[0021] Preferably, the praseodymium salt in step (1) includes any one of Pr2(CO3)3, Pr(NO3)3, PrCl3 or Pr2(SO4)3, or a combination of at least two thereof.

[0022] Preferably, the neodymium salt in step (1) includes any one of Nd2(CO3)3, Nd(NO3)3, NdCl3 or Nd2(SO4)3, or a combination of at least two of them.

[0023] Preferably, the mass ratio of the cerium salt to the solvent in step (1) is 1:(100-200), for example, 1:100, 1:110, 1:120, 1:130, 1:140, 1:150, 1:160, 1:170, 1:180, 1:190 or 1:200, etc.

[0024] In the present invention, if the mass ratio of the cerium salt to the solvent is too low and the amount of solvent added is too much, the reaction rate will be low and the reaction yield will be low. Even when the amount of cerium salt added is extremely low, spherical cerium dioxide particles cannot be obtained. If the mass ratio of the two is too high and the amount of solvent added is too low, the reaction rate will be too fast, but the uniformity of the product particles will be poor.

[0025] Preferably, the specific process of the first mixing in step (1) includes: mixing the cerium salt, the doping metal salt, the solvent and the inorganic acid, and then adding the organic acid and continuing to mix to obtain the first mixture.

[0026] In the preparation of spherical cerium dioxide, the present invention adopts a mixing process of adding an inorganic acid first and then an organic acid, which is beneficial to preparing spherical cerium dioxide with uniform particle morphology and improving the particle uniformity of the spherical cerium dioxide.

[0027] Preferably, the cerium salt, the doping metal salt, the solvent and the inorganic acid are mixed for 1-6 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0028] Preferably, the time for adding the organic acid and continuing mixing is 6-18 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours or 18 hours, etc.

[0029] Preferably, the volume ratio of the inorganic acid to the organic acid is (1.5-2.5):1, for example, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1 or 2.5:1, etc.

[0030] In the preparation of quasi-spherical cerium dioxide of the present invention, if the volume ratio of the inorganic acid to the organic acid is too low, and the amount of the inorganic acid added is too little, the reaction speed is slowed down, resulting in incomplete reaction for preparing the quasi-spherical cerium dioxide, affecting the preparation of the quasi-spherical cerium dioxide; if the volume ratio of the inorganic acid to the organic acid is too high, and the amount of the organic acid added is too little, the content of the quasi-spherical cerium dioxide in the final product is reduced, the product purity is low, and the particle uniformity of the quasi-spherical cerium dioxide is also deteriorated.

[0031] Preferably, the inorganic acid comprises nitric acid.

[0032] Preferably, the concentration of the inorganic acid is 0.1-20wt%, for example 0.1wt%, 1wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, etc.

[0033] Preferably, the organic acid includes any one of formic acid, acetic acid, n-butyric acid, n-hexanoic acid or oxalic acid.

[0034] Preferably, the concentration of the organic acid is 0.1-20wt%, for example 0.1wt%, 1wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, etc.

[0035] Preferably, the ratio of the total volume of the inorganic acid and the organic acid in step (1) to the volume of the solvent is 3:(220-280), for example 3:220, 3:225, 3:230, 3:235, 3:240, 3:245, 3:250, 3:255, 3:260, 3:265, 3:270, 3:275 or 3:280, etc.

[0036] In the present invention, if the ratio of the total volume of the inorganic acid and the organic acid to the volume of the solvent is too low, and the amount of acid added is relatively too much, it will affect the preparation of quasi-spherical cerium dioxide, resulting in the generation of impurities during the reaction process of preparing quasi-spherical cerium dioxide and low product purity; if the volume ratio of the two is too high, and the amount of acid added is relatively too low, it will lead to a decrease in the reaction rate, incomplete reaction during the preparation of quasi-spherical cerium dioxide, and will also affect the purity of the obtained product.

[0037] Preferably, the rotation speed of the first mixing in step (1) is 200-600 rpm, for example, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm or 600 rpm, etc.

[0038] In the present invention, if the rotation speed of the first mixing in step (1) is too low, the uniformity of the raw material mixing is poor, and ultimately the morphological uniformity of the obtained spherical cerium dioxide is poor, and the consistency of the particle size is poor; if the rotation speed of the first mixing in step (1) is too high, foam and microbubbles are likely to occur during the mixing process, affecting the reaction of the spherical cerium dioxide, thereby affecting the morphology and performance of the obtained particles.

[0039] Preferably, the specific process of the second mixing in step (2) includes: under the hydrothermal conditions, the ammonia water and the ammonium salt are simultaneously mixed with the first mixture for a second time to obtain the second mixture.

[0040] In the preparation method of quasi-spherical cerium dioxide of the present invention, if either ammonia water or ammonium salt is lacking, the reaction rate will be reduced, the reaction will be insufficient, the particle morphology will change, and quasi-spherical cerium dioxide with high purity cannot be obtained.

[0041] Preferably, the mass ratio of the ammonia water to the ammonium salt in step (2) is (3.5-4.5):2, for example, 3.5:2, 3.6:2, 3.7:2, 3.8:2, 3.9:2, 4.0:2, 4.1:2, 4.2:2, 4.3:2, 4.4:2 or 4.5:2, etc.

[0042] In the present invention, if the mass ratio of ammonia water to ammonium salt is too low, and the amount of ammonia water added is relatively too small, the reaction for preparing quasi-spherical cerium dioxide will be incomplete, and quasi-spherical cerium dioxide with high purity and good crystallinity cannot be obtained; if the mass ratio of ammonia water to ammonium salt is too high, and the amount of ammonium salt added is relatively too small, the reaction speed for preparing quasi-spherical cerium dioxide will be reduced, affecting the production efficiency, and affecting the morphology of the cerium dioxide obtained subsequently.

[0043] Preferably, the concentration of the aqueous ammonia is 1-35wt%, for example, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt% or 35wt%, etc.

[0044] Preferably, the temperature of the hydrothermal condition in step (2) is 30-100°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, etc.

[0045] In the present invention, if the temperature of the hydrothermal conditions is too low, the reaction will not occur and a highly active intermediate will not be obtained, thereby affecting the preparation of spherical cerium dioxide; if the temperature is too high, energy consumption will increase and the product morphology will deteriorate.

[0046] Preferably, the pressure of the hydrothermal conditions in step (2) is 0.1-20 MPa, for example, 0.1 MPa, 0.5 MPa, 1 MPa, 2 MPa, 4 MPa, 6 MPa, 8 MPa, 10 MPa, 12 MPa, 14 MPa, 16 MPa, 18 MPa or 20 MPa, etc.

[0047] Preferably, the second mixing time in step (2) is 0.1-5 h, for example, 0.1 h, 0.5 h, 1 h, 1.5 h, 2 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h.

[0048] The present invention adjusts the pH of the obtained second mixture to be within a specific range by adjusting the relative contents of the first mixture, ammonia water and ammonium salt.

[0049] Preferably, the temperature of the sol-gel reaction in step (2) is 50-160°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or 160°C, etc.

[0050] Preferably, the pH during the sol-gel reaction in step (2) is maintained at 8-10, for example, 8, 8.2, 8.4, 8.6, 8.8, 9, 9.2, 9.4, 9.6, 9.8 or 10.

[0051] In the present invention, the pH of the reactants during the sol-gel reaction can be regulated and maintained within a specific range by adding ammonia water and nitric acid to the raw materials.

[0052] Preferably, the sol-gel reaction in step (2) is also accompanied by stirring.

[0053] Preferably, the stirring speed is 10-500rpm, for example, 10rpm, 20rpm, 50rpm, 100rpm, 150rpm, 200rpm, 250rpm, 300rpm, 350rpm, 400rpm, 450rpm or 500rpm, etc.

[0054] In the preparation of quasi-spherical cerium dioxide in the present invention, if the stirring speed during the sol-gel reaction is too low, it will lead to incomplete reaction, thereby affecting the morphology of cerium dioxide and also causing the uniformity of the obtained quasi-spherical cerium dioxide particles to decrease; if the stirring speed during the sol-gel reaction is too high, bubbles will be generated to affect the reaction between substances, thereby affecting the morphology and performance of the obtained cerium dioxide.

[0055] In the present invention, the sol-gel reaction of step (2) is still carried out in the hydrothermal reactor, and only the reaction temperature is adjusted and the stirring process is added.

[0056] Preferably, the sol-gel reaction in step (2) is carried out until the solid content of the obtained spherical cerium dioxide sol is 0.1-40wt%, for example, 0.1wt%, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt% or 40wt%, etc.

[0057] Preferably, the specific process of the post-treatment in step (3) includes: concentrating the quasi-spherical cerium dioxide sol obtained in step (2), and then centrifuging, drying and deagglomerating to obtain the quasi-spherical cerium dioxide.

[0058] Preferably, the concentration temperature is 120-180°C, such as 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C.

[0059] Preferably, the concentration pressure is 0.1-100 MPa, for example, 0.1 MPa, 0.5 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa or 100 MPa.

[0060] Preferably, the concentration is performed until the solid content of the concentrated product is ≥ 60wt%, for example 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt% or 95wt%, etc.

[0061] In the preparation of spherical cerium dioxide, the solid content of the concentrated product is regulated to facilitate separation of nanoparticles after centrifugation. If the solid content of the concentrated product is too low, the yield of spherical cerium dioxide will be reduced.

[0062] Preferably, the centrifugal rotation speed is 500-5000 rpm, for example, 500 rpm, 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm or 5000 rpm, etc.

[0063] Preferably, the drying temperature is 300-1100°C, for example, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C or 1100°C.

[0064] Preferably, the drying time is 2-12 h, for example, 2 h, 4 h, 6 h, 8 h, 10 h or 12 h.

[0065] Preferably, the deagglomeration method includes any one of gas phase injection, convection injection or air grinding.

[0066] In a second aspect, the present invention provides a quasi-spherical cerium dioxide, wherein the quasi-spherical cerium dioxide is prepared by the preparation method described in the first aspect, and the quasi-spherical cerium dioxide comprises doping elements, wherein the doping elements comprise praseodymium and / or neodymium.

[0067] The quasi-spherical cerium dioxide provided by the present invention has a regular morphology, good particle uniformity, high crystallinity and high purity, wherein specific praseodymium and / or neodymium elements as doping elements of cerium dioxide can promote the regulation of the morphology of cerium dioxide and improve the crystallinity of the obtained quasi-spherical cerium dioxide particles.

[0068] Preferably, the particle size D50 of the spherical cerium dioxide is 5-500 nm, for example, 5 nm, 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm.

[0069] Preferably, the specific surface area of ​​the spherical cerium dioxide is 20-250m 2 / g, for example 20m 2 / g, 40m 2 / g, 60m 2 / g, 80m 2 / g、100m 2 / g, 120m 2 / g, 140m 2 / g, 160m 2 / g, 180m 2 / g, 200m 2 / g, 220m 2 / g, 240m 2 / g or 250m 2 / g, etc.

[0070] In a third aspect, the present invention provides an application of the quasi-spherical cerium oxide according to the second aspect, wherein the quasi-spherical cerium oxide is applied in semiconductor chemical mechanical polishing (CMP), optical polishing or cosmetics.

[0071] The quasi-spherical cerium dioxide provided by the present invention is suitable for any application field that can be thought of by those skilled in the art.

[0072] The second object of the present invention is to provide a hexagonal cerium dioxide and its preparation method and application. The preparation method adopted by the present invention introduces a doping metal salt into a cerium salt, and then mixes it with an inorganic acid and an organic acid, the obtained product is mixed with ammonia water and an ammonium salt under hydrothermal conditions, and the pH of the obtained mixture is subjected to a sol-gel reaction under weak acid conditions within a specific range to obtain a hexagonal cerium dioxide sol, and then combined with a post-treatment process to obtain hexagonal cerium dioxide particles, the particles of which have regular shape, good size uniformity, and high purity and crystallinity.

[0073] To achieve this object, the present invention adopts the following technical solutions:

[0074] In a fourth aspect, the present invention provides a method for preparing hexagonal cerium dioxide, the preparation method comprising the following steps:

[0075] (1) mixing a cerium salt, a doping metal salt, a solvent, an inorganic acid and an organic acid to obtain a first mixture;

[0076] The doping metal salt includes praseodymium salt and / or neodymium salt;

[0077] (2) under hydrothermal conditions, mixing the first mixture with ammonia water and ammonium salt to obtain a second mixture, wherein the pH value of the second mixture is 3.5-6, and performing a sol-gel reaction to obtain a hexagonal cerium dioxide sol;

[0078] (3) Post-treating the hexagonal cerium dioxide sol to obtain the hexagonal cerium dioxide.

[0079] In the present invention, the pH range can be selected from "3.5-6", such as 3.5, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5.0, 5.2, 5.4, 5.6, 5.8 or 6.

[0080] The preparation method provided by the present invention introduces specific praseodymium salt and / or neodymium salt as doping metal salt into cerium salt, promotes the regulation of product morphology in the subsequent reaction process and can improve the crystallinity of the obtained product, and then mixes the cerium salt and the doping metal salt with inorganic acid and organic acid in a solvent to obtain a composite cerium salt and a composite doping metal salt containing both inorganic acid radicals and organic acid radicals, and then under hydrothermal conditions, the composite cerium salt and the composite doping metal salt can react with ammonia water and ammonium salt to obtain a highly active intermediate, and the pH value in the reaction solution is precisely regulated to be within the range of 3.5-6, and a sol-gel reaction is carried out under weakly acidic conditions of a specific pH value, and the highly active intermediate can stably crystallize to form a cerium dioxide seed crystal with a specific shape, and the seed crystal maintains the specific shape and continues to grow uniformly to form a hexagonal crystal nucleus with uniform size and regular morphology, and the crystal nucleus is gelled to obtain a hexagonal cerium dioxide sol, and the obtained sol is further subjected to a post-treatment process to finally obtain hexagonal cerium dioxide particles with high purity and crystallinity. The preparation method adopted by the present invention has short reaction time, simple operation and easy mass production. The prepared cerium dioxide has a hexagonal morphology with regular shape, good particle uniformity, high crystallinity and purity, and can be widely used in semiconductor CMP polishing, high-end optical polishing or cosmetics and other fields.

[0081] Preferably, the ratio of the molar amount of cerium ions in the cerium salt in step (1) to the total molar amount of doped metal ions in the doped metal salt is (500-50000):1, for example, 500:1, 1000:1, 5000:1, 10000:1, 15000:1, 20000:1, 25000:1, 30000:1, 35000:1, 40000:1, 45000:1 or 500000:1, etc.

[0082] In the present invention, if the molar ratio of cerium ions in the cerium salt to the doped metal ions in the doped metal salt is too low, the particles will not be able to be formed, affecting the growth morphology of hexagonal cerium dioxide, and hexagonal cerium dioxide with excellent performance cannot be obtained; if the molar ratio of the two is too high, the crystallinity of the obtained hexagonal cerium dioxide will deteriorate, and the morphology of cerium dioxide will be affected.

[0083] Preferably, the doping metal salt in step (1) comprises praseodymium salt and neodymium salt.

[0084] Preferably, when the doped metal salt includes praseodymium salt and neodymium salt, the molar ratio of praseodymium ions in the praseodymium salt to neodymium ions in the neodymium salt is (1-10):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc.

[0085] Preferably, the cerium salt in step (1) includes any one of Ce2(CO3)3, Ce(NO3)3, CeCl3 or Ce2(SO4)3, or a combination of at least two thereof.

[0086] Preferably, the praseodymium salt in step (1) includes any one of Pr2(CO3)3, Pr(NO3)3, PrCl3 or Pr2(SO4)3, or a combination of at least two thereof.

[0087] Preferably, the neodymium salt in step (1) includes any one of Nd2(CO3)3, Nd(NO3)3, NdCl3 or Nd2(SO4)3, or a combination of at least two of them.

[0088] Preferably, the mass ratio of the cerium salt to the solvent in step (1) is 1:(100-200), for example, 1:100, 1:110, 1:120, 1:130, 1:140, 1:150, 1:160, 1:170, 1:180, 1:190 or 1:200, etc.

[0089] Preferably, the specific process of the first mixing in step (1) includes: mixing the cerium salt, the doping metal salt, the solvent and the organic acid, and then adding the inorganic acid and continuing to mix to obtain the first mixture.

[0090] In the preparation of hexagonal cerium dioxide, the present invention adopts a mixing process of first adding an organic acid and then adding an inorganic acid, which is conducive to forming hexagonal cerium dioxide with good morphology identity and high particle uniformity in the subsequent process.

[0091] Preferably, the cerium salt, the doping metal salt, the solvent and the organic acid are mixed for 1-6 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0092] Preferably, the time for adding the inorganic acid and continuing mixing is 12-24 hours, for example, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours or 24 hours, etc.

[0093] Preferably, the volume ratio of the inorganic acid to the organic acid is (2.8-4):1, for example, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1 or 4:1, etc.

[0094] In the preparation of hexagonal cerium dioxide in the present invention, if the volume ratio of the inorganic acid to the organic acid is too low, and the amount of the inorganic acid added is relatively too small, the reaction for preparing the hexagonal cerium dioxide will be incomplete, affecting the preparation of the hexagonal cerium dioxide; if the volume ratio of the inorganic acid to the organic acid is too high, and the amount of the organic acid added is relatively too small, the content of the hexagonal cerium dioxide in the final product will be reduced, the product purity will be low, and the particle size uniformity of the hexagonal cerium dioxide will be affected.

[0095] Preferably, the inorganic acid comprises nitric acid.

[0096] Preferably, the concentration of the inorganic acid is 0.1-20wt%, for example 0.1wt%, 1wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, etc.

[0097] Preferably, the organic acid includes any one of formic acid, acetic acid, n-butyric acid, n-hexanoic acid or oxalic acid.

[0098] Preferably, the concentration of the organic acid is 0.1-20wt%, for example 0.1wt%, 1wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, etc.

[0099] Preferably, the ratio of the total volume of the inorganic acid and the organic acid in step (1) to the volume of the solvent is 3:(150-210), for example 3:150, 3:155, 3:160, 3:165, 3:170, 3:175, 3:180, 3:185, 3:190, 3:195, 3:200, 3:205 or 3:210, etc.

[0100] In the present invention, if the ratio of the total volume of the inorganic acid and the organic acid to the volume of the solvent is too low, and the amount of acid added is relatively too much, it will affect the preparation of hexagonal cerium dioxide, resulting in an increase in the impurity content during the reaction process of preparing hexagonal cerium dioxide and a decrease in the purity of the obtained hexagonal cerium dioxide particles; if the volume ratio of the two is too high and the amount of acid added is relatively too low, it will lead to a decrease in the reaction rate, incomplete reaction during the preparation of hexagonal cerium dioxide, and affect the purity of the obtained hexagonal cerium dioxide.

[0101] Preferably, the rotation speed of the first mixing in step (1) is 1000-15000 rpm, for example, 1000 rpm, 2000 rpm, 3000 rpm, 4000 rpm, 5000 rpm, 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, 11000 rpm, 12000 rpm, 13000 rpm, 14000 rpm or 15000 rpm, etc.

[0102] In the preparation of hexagonal cerium dioxide in the present invention, if the rotation speed of the first mixing in step (1) is too low, the morphological identity and size uniformity of the hexagonal cerium dioxide will be affected; if the rotation speed of the first mixing in step (1) is too high, a large number of microbubbles will be generated, affecting the reaction process of preparing hexagonal cerium dioxide.

[0103] Preferably, the specific process of the second mixing in step (2) includes: under the hydrothermal conditions, first mixing the first mixture with the ammonium salt, and then adding the ammonia water to the obtained mixed product to mix, so as to obtain the second mixture.

[0104] In the preparation method of hexagonal cerium dioxide of the present invention, in the hydrothermal reaction, a process of first mixing the first mixture with the ammonium salt and then adding ammonia water for mixing is adopted, aiming at controlling the reaction speed and reaction process, thereby being conducive to the preparation of hexagonal cerium dioxide with good particle uniformity.

[0105] Preferably, the first mixture and the ammonium salt are mixed for 0.5-3 h, such as 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h or 3 h.

[0106] Preferably, the time for adding ammonia water to the product obtained by mixing the first mixture and the ammonium salt to mix is ​​0.1-3 hours, such as 0.1 hours, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours.

[0107] Preferably, the mass ratio of the ammonia water to the ammonium salt is (4.8-6):2, for example, 4.8:2, 5:2, 5.2:2, 5.4:2, 5.6:2, 5.8:2 or 6:2, etc.

[0108] In the preparation method of hexagonal cerium dioxide of the present invention, if the mass ratio of ammonia water to ammonium salt is too low or too high, the reaction process of the preparation process of hexagonal cerium dioxide will be affected, resulting in incomplete reaction of preparing hexagonal cerium dioxide, thereby affecting the morphology and purity of cerium dioxide.

[0109] Preferably, the concentration of the aqueous ammonia is 1-35wt%, for example, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt% or 35wt%, etc.

[0110] Preferably, the temperature of the hydrothermal condition in step (2) is 30-100°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, etc.

[0111] In the present invention, if the temperature of the hydrothermal conditions is too low, the reaction will not occur and a highly active intermediate will not be obtained, thereby affecting the preparation of hexagonal cerium dioxide; if the temperature is too high, it will lead to increased energy consumption and poor product morphology identity.

[0112] Preferably, the pressure of the hydrothermal conditions in step (2) is 0.1-20 MPa, for example, 0.1 MPa, 0.5 MPa, 1 MPa, 2 MPa, 4 MPa, 6 MPa, 8 MPa, 10 MPa, 12 MPa, 14 MPa, 16 MPa, 18 MPa or 20 MPa, etc.

[0113] The present invention adjusts the pH of the obtained second mixture to be within a specific range by adjusting the relative contents of the first mixture, ammonia water and ammonium salt.

[0114] Preferably, the temperature of the sol-gel reaction in step (2) is 50-160°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or 160°C, etc.

[0115] Preferably, the pH during the sol-gel reaction in step (2) is maintained at 3.5-6, for example, 3.5, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5.0, 5.2, 5.4, 5.6, 5.8 or 6.

[0116] In the present invention, the pH of the reactants during the sol-gel reaction can be regulated and maintained within a specific range by adding ammonia water and nitric acid to the raw materials.

[0117] Preferably, the sol-gel reaction in step (2) is also accompanied by stirring.

[0118] Preferably, the stirring speed is 200-2000 rpm, for example, 200 rpm, 400 rpm, 600 rpm, 800 rpm, 1000 rpm, 1200 rpm, 1400 rpm, 1600 rpm, 1800 rpm or 2000 rpm, etc.

[0119] In the preparation of hexagonal cerium dioxide in the present invention, if the stirring speed during the sol-gel reaction is relatively too low, the identity of the morphology and the uniformity of the particle size of the obtained hexagonal cerium dioxide particles will decrease; if the stirring speed during the sol-gel reaction is too high, the uniformity of the particle size will decrease.

[0120] In the present invention, the sol-gel reaction of step (2) is still carried out in the hydrothermal reactor, and only the reaction temperature is adjusted and the stirring process is added.

[0121] Preferably, the sol-gel reaction in step (2) is carried out until the solid content of the obtained hexagonal cerium dioxide sol is 0.1-40wt%, for example, 0.1wt%, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt% or 40wt%, etc.

[0122] Preferably, the specific process of the post-treatment in step (3) includes: concentrating the hexagonal cerium dioxide sol obtained in step (2), and then centrifuging, drying and deagglomerating to obtain the hexagonal cerium dioxide.

[0123] Preferably, the concentration temperature is 120-180°C, such as 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C.

[0124] Preferably, the concentration pressure is 0.1-100 MPa, for example, 0.1 MPa, 1 MPa, 5 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa or 100 MPa.

[0125] Preferably, the concentration is performed until the solid content of the concentrated product is ≥ 60wt%, for example 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt% or 95wt%, etc.

[0126] In the preparation of hexagonal cerium dioxide, the solid content of the concentrated product is regulated to facilitate separation of nanoparticles after centrifugation. If the solid content of the concentrated product is too low, the final yield of hexagonal cerium dioxide will be reduced.

[0127] Preferably, the centrifugal rotation speed is above 2000 rpm, for example, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm or 5000 rpm.

[0128] Preferably, the drying temperature is 300-1100°C, for example, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C or 1100°C.

[0129] Preferably, the drying time is 2-12 h, for example, 2 h, 4 h, 6 h, 8 h, 10 h or 12 h.

[0130] Preferably, the specific process of deagglomeration includes any one of gas phase injection, convection injection or air grinding.

[0131] In a fifth aspect, the present invention provides a hexagonal cerium dioxide, wherein the hexagonal cerium dioxide is prepared by the preparation method described in the fourth aspect, and the hexagonal cerium dioxide includes a doping element, and the doping element includes praseodymium and / or neodymium.

[0132] The hexagonal cerium dioxide provided by the present invention has regular morphology, good particle uniformity, high crystallinity and high purity, wherein specific praseodymium and / or neodymium elements as doping elements of cerium dioxide can promote the regulation of cerium dioxide morphology and improve the crystallinity of the obtained hexagonal cerium dioxide particles.

[0133] Preferably, the particle size D50 of the hexagonal cerium dioxide is 5-500 nm, for example, 5 nm, 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm.

[0134] Preferably, the side length of the hexagonal cerium dioxide is 60-160 nm, for example, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm or 160 nm.

[0135] Preferably, the thickness of the hexagonal cerium dioxide is 2-20 nm, for example, 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm or 20 nm.

[0136] Preferably, the specific surface area of ​​the hexagonal cerium dioxide is 100-250m 2 / g, for example 100m 2 / g, 110m 2 / g, 120m 2 / g, 130m 2 / g, 140m 2 / g, 150m 2 / g, 160m 2 / g, 170m 2 / g, 180m 2 / g, 190m 2 / g, 200m 2 / g, 210m 2 / g, 220m 2 / g, 230m 2 / g, 240m 2 / g or 250m 2 / g, etc.

[0137] In a sixth aspect, the present invention provides an application of the hexagonal cerium oxide according to the fifth aspect, wherein the hexagonal cerium oxide is applied in semiconductor chemical mechanical polishing (CMP), optical polishing or cosmetics.

[0138] The hexagonal cerium dioxide provided by the present invention is suitable for any application field that can be thought of by those skilled in the art.

[0139] The third object of the present invention is to provide a triangular cerium dioxide and its preparation method and application. The preparation method adopted by the present invention introduces a doping metal salt into a cerium salt, and then mixes it with an inorganic acid and an organic acid, the obtained product is mixed with ammonia water and an ammonium salt under hydrothermal conditions, and the pH of the obtained mixture is subjected to a sol-gel reaction under a strong acid condition within a specific range to obtain a triangular cerium dioxide sol, and then combined with a post-treatment process to obtain triangular cerium dioxide particles, the particles of which have a regular shape, good size uniformity, and high purity and crystallinity.

[0140] To achieve this object, the present invention adopts the following technical solutions:

[0141] In a seventh aspect, the present invention provides a method for preparing triangular cerium dioxide, the preparation method comprising the following steps:

[0142] (1) mixing a cerium salt, a doping metal salt, a solvent, an inorganic acid and an organic acid to obtain a first mixture;

[0143] The doping metal salt includes praseodymium salt and / or neodymium salt;

[0144] (2) under hydrothermal conditions, mixing the first mixture with ammonia water and ammonium salt to obtain a second mixture, wherein the pH value of the second mixture is 1-3, and performing a sol-gel reaction to obtain a triangular cerium dioxide sol;

[0145] (3) Post-treating the triangular cerium dioxide sol to obtain the triangular cerium dioxide.

[0146] In the present invention, the pH value may be selected in the range of "1-3", such as 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8 or 3.

[0147] The preparation method provided by the present invention is to mix cerium salt and doped metal salt with inorganic acid and organic acid in a solvent to obtain a composite cerium salt and a composite doped metal salt containing both inorganic acid radicals and organic acid radicals, and then under hydrothermal conditions, the composite cerium salt and the composite doped metal salt react with ammonia water and ammonium salt to obtain a highly active intermediate, and the pH value in the reaction solution is precisely controlled to be within the range of 1-3, and a sol-gel reaction is performed under a strong acidic condition of a specific pH, and the highly active intermediate can stably crystallize to form a specific shape of cerium dioxide seeds, and the seeds maintain a specific shape and continue to grow uniformly to form a triangular crystal nucleus with uniform size and regular morphology, and the crystal nucleus is gelled to obtain a triangular cerium dioxide sol, and the obtained sol is then subjected to a post-treatment process, and finally a large number of triangular cerium dioxide particles with high purity and crystallinity are obtained. The present invention also introduces a specific praseodymium salt and / or neodymium salt as a doped metal salt in the cerium salt to promote the regulation of the product morphology and to improve the crystallinity of the product, thereby facilitating the polishing effect of the obtained material. The preparation method adopted by the present invention has short reaction time, simple operation and easy mass production. The prepared cerium dioxide has a triangular morphology with regular shape, uniform particles, good crystallinity and high purity, and can be widely used in semiconductor CMP polishing, high-end optical polishing or cosmetics and other fields.

[0148] Preferably, the ratio of the molar amount of cerium ions in the cerium salt in step (1) to the total molar amount of doped metal ions in the doped metal salt is (1000-500000):1, for example, 1000:1, 5000:1, 10000:1, 5000:1, 10000:1, 200000:1, 300000:1, 400000:1 or 500000:1, etc.

[0149] In the present invention, if the molar ratio of cerium ions in the cerium salt to the doped metal ions in the doped metal salt is too low, the particles will not be able to be formed, affecting the growth morphology of cerium dioxide, and even failing to obtain triangular cerium dioxide; if the molar ratio of the two is too high, the crystallinity of the obtained product will be poor, and it may even be unable to be applied to the polishing field, and it will also affect the morphology of cerium dioxide.

[0150] Preferably, the doping metal salt in step (1) comprises praseodymium salt and neodymium salt.

[0151] Preferably, when the doped metal salt includes praseodymium salt and neodymium salt, the molar ratio of praseodymium ions in the praseodymium salt to neodymium ions in the neodymium salt is (1-10):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, etc.

[0152] Preferably, the cerium salt in step (1) includes any one of Ce2(CO3)3, Ce(NO3)3, CeCl3 or Ce2(SO4)3, or a combination of at least two thereof.

[0153] Preferably, the praseodymium salt in step (1) includes any one of Pr2(CO3)3, Pr(NO3)3, PrCl3 or Pr2(SO4)3, or a combination of at least two thereof.

[0154] Preferably, the neodymium salt in step (1) includes any one of Nd2(CO3)3, Nd(NO3)3, NdCl3 or Nd2(SO4)3, or a combination of at least two of them.

[0155] Preferably, the mass ratio of the cerium salt to the solvent in step (1) is 1:(100-200), for example, 1:100, 1:110, 1:120, 1:130, 1:140, 1:150, 1:160, 1:170, 1:180, 1:190 or 1:200, etc.

[0156] Preferably, the specific process of the first mixing in step (1) includes: mixing the cerium salt, the doping metal salt, the solvent and the organic acid, and then adding the inorganic acid and continuing to mix to obtain the first mixture.

[0157] Preferably, the cerium salt, the doping metal salt, the solvent and the organic acid are mixed for 1-6 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours.

[0158] Preferably, the time for adding the inorganic acid and continuing mixing is 12-24 hours, for example, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours or 24 hours, etc.

[0159] In the preparation of triangular cerium dioxide, the present invention adopts a mixing process of first adding an organic acid and then adding an inorganic acid, aiming at controlling the reaction speed and improving the uniformity of the prepared triangular cerium dioxide particles.

[0160] Preferably, the volume ratio of the inorganic acid to the organic acid is (6-10):3, for example, 6:3, 6.5:3, 7:3, 7.5:3, 8:3, 8.5:3, 9:3, 9.5:3 or 10:3, etc.

[0161] In the preparation process of triangular cerium dioxide, the volume ratio of inorganic acid and organic acid is regulated to control the reaction and avoid the relative volume of inorganic acid and organic acid being too low or too high to affect the morphology and particle uniformity of the prepared triangular cerium dioxide.

[0162] Preferably, the inorganic acid comprises nitric acid.

[0163] Preferably, the concentration of the inorganic acid is 0.1-20wt%, for example 0.1wt%, 1wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, etc.

[0164] Preferably, the organic acid includes any one of formic acid, acetic acid, n-butyric acid, n-hexanoic acid or oxalic acid.

[0165] Preferably, the concentration of the organic acid is 0.1-20wt%, for example 0.1wt%, 1wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, etc.

[0166] Preferably, the ratio of the total volume of the inorganic acid and the organic acid in step (1) to the volume of the solvent is 3:(80-140), for example 3:80, 3:85, 3:90, 3:95, 3:100, 3:105, 3:110, 3:115, 3:120, 3:125, 3:130, 3:135 or 3:140, etc.

[0167] In the present invention, if the ratio of the total volume of the inorganic acid and the organic acid to the volume of the solvent is too low, and the amount of acid added is too much, it will affect the preparation of triangular cerium dioxide, resulting in the generation of impurities during the reaction process of preparing triangular cerium dioxide and low product purity; if the volume ratio of the two is too high and the amount of acid added is too low, the reaction rate will decrease, the reaction in the process of preparing triangular cerium dioxide will be incomplete, and the purity of the obtained product will also be affected.

[0168] Preferably, the rotation speed of the first mixing in step (1) is 1000-2000 rpm, for example, 1000 rpm, 1200 rpm, 1400 rpm, 1600 rpm, 1800 rpm or 2000 rpm.

[0169] In the present invention, if the rotation speed of the first mixing in step (1) is too low, the reaction process in the preparation process of triangular cerium dioxide will be affected, thereby affecting the morphology and particle size uniformity of the triangular cerium dioxide; if the rotation speed of the first mixing in step (1) is too high, a large number of microbubbles will be generated, causing the particle size uniformity of the prepared triangular cerium dioxide particles to decrease.

[0170] Preferably, the specific process of the second mixing in step (2) includes: under the hydrothermal conditions, first mixing the first mixture with the ammonia water, and then adding the ammonium salt to the obtained mixed product to obtain the second mixture.

[0171] In the preparation method of triangular cerium dioxide of the present invention, under hydrothermal conditions, the first mixture is first mixed with ammonia water, and then ammonium salt is added for mixing, aiming at controlling the reaction process, thereby facilitating the preparation of triangular cerium dioxide with excellent morphology and performance.

[0172] Preferably, the first mixture and the aqueous ammonia are mixed for 0.5-3 h, such as 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h or 3 h.

[0173] Preferably, the mixing time for adding ammonium salt to the product obtained by mixing the first mixture and the ammonia water is 0.1-3h, for example, 0.1h, 0.5h, 1h, 1.5h, 2h, 2.5h or 3h.

[0174] Preferably, the mass ratio of the ammonia water to the ammonium salt is (8-12):2, for example 8:2, 8.5:2, 9:2, 9.5:2, 10:2, 10.5:2, 11:2, 11.5:2 or 12:2, etc.

[0175] In the preparation method of triangular cerium dioxide of the present invention, if the mass ratio of ammonia water to ammonium salt is too low or too high, the reaction process of the preparation process of triangular cerium dioxide will be affected, thereby affecting the morphology and purity of triangular cerium dioxide.

[0176] Preferably, the concentration of the aqueous ammonia is 1-35wt%, for example, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt% or 35wt%, etc.

[0177] Preferably, the temperature of the hydrothermal condition in step (2) is 30-100°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C, etc.

[0178] Preferably, the pressure of the hydrothermal conditions in step (2) is 0.1-20 MPa, for example, 0.1 MPa, 0.5 MPa, 1 MPa, 2 MPa, 4 MPa, 6 MPa, 8 MPa, 10 MPa, 12 MPa, 14 MPa, 16 MPa, 18 MPa or 20 MPa, etc.

[0179] The present invention adjusts the pH of the obtained second mixture to be within a specific range by adjusting the relative contents of the first mixture, ammonia water and ammonium salt.

[0180] Preferably, the temperature of the sol-gel reaction in step (2) is 50-160°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or 160°C, etc.

[0181] Preferably, the pH during the sol-gel reaction in step (2) is maintained at 1-3, for example, 1, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8 or 3.

[0182] In the present invention, the pH of the reactants during the sol-gel reaction can be regulated and maintained within a specific range by adding ammonia water and nitric acid to the raw materials.

[0183] Preferably, the sol-gel reaction in step (2) is also accompanied by stirring.

[0184] Preferably, the stirring speed is 300-3000 rpm, for example, 300 rpm, 600 rpm, 900 rpm, 1200 rpm, 1500 rpm, 1800 rpm, 2100 rpm, 2400 rpm, 2700 rpm or 3000 rpm, etc.

[0185] In the preparation of triangular cerium dioxide of the present invention, if the stirring speed during the sol-gel reaction is relatively too low, the identity of the morphology and the uniformity of the particle size of the obtained triangular cerium dioxide particles will decrease; if the stirring speed during the sol-gel reaction is too high, the uniformity of the particle size will decrease.

[0186] In the present invention, the sol-gel reaction of step (2) is still carried out in the hydrothermal reactor, and only the reaction temperature is adjusted and the stirring process is added.

[0187] Preferably, the sol-gel reaction in step (2) is carried out until the solid content of the obtained triangular cerium dioxide sol is 0.1-40wt%, for example, 0.1wt%, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt% or 40wt%, etc.

[0188] Preferably, the specific process of the post-treatment includes: concentrating the triangular cerium dioxide sol obtained in step (2), and then centrifuging, drying and deagglomerating to obtain the triangular cerium dioxide.

[0189] Preferably, the concentration temperature is 120-180°C, such as 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C.

[0190] Preferably, the concentration pressure is 0.1-100 MPa, for example, 0.1 MPa, 1 MPa, 5 MPa, 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa or 100 MPa.

[0191] Preferably, the concentration is performed until the solid content of the concentrated product is ≥ 60wt%, for example 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt% or 95wt%, etc.

[0192] In the preparation of triangular cerium dioxide, the solid content of the concentrated product is regulated to facilitate separation of nanoparticles after centrifugation. If the solid content of the concentrated product is too low, the final yield of triangular cerium dioxide will be reduced.

[0193] Preferably, the centrifugal rotation speed is 2000-6000 rpm, for example, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm or 6000 rpm, etc.

[0194] Preferably, the drying temperature is 300-1100°C, for example, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C or 1100°C.

[0195] Preferably, the drying time is 2-12 h, for example, 2 h, 4 h, 6 h, 8 h, 10 h or 12 h.

[0196] In an eighth aspect, the present invention provides a triangular cerium dioxide, wherein the triangular cerium dioxide is prepared by the preparation method described in the seventh aspect, and the triangular cerium dioxide includes a doping element, and the doping element includes praseodymium and / or neodymium.

[0197] The triangular cerium dioxide provided by the present invention has regular morphology, good particle uniformity, high crystallinity and high purity, wherein specific praseodymium and / or neodymium elements are used as doping elements of cerium dioxide to promote the regulation of cerium dioxide morphology and improve the crystallinity of the obtained triangular cerium dioxide particles.

[0198] Preferably, the particle size D50 of the triangular cerium dioxide is 5-500 nm, for example, 5 nm, 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm.

[0199] Preferably, the triangular cerium dioxide includes triangular nano-sheet cerium dioxide and / or triangular pyramid cerium dioxide.

[0200] Preferably, the triangular cerium dioxide includes triangular nano-sheet cerium dioxide and triangular pyramid cerium dioxide.

[0201] Preferably, the mass ratio of the triangular nanosheet cerium dioxide to the triangular pyramid cerium dioxide is 2:(0.1-1), for example, 2:0.1, 2:0.2, 2:0.3, 2:0.4, 2:0.5, 2:0.6, 2:0.7, 2:0.8, 2:0.9 or 2:1, etc.

[0202] Preferably, the triangular nanosheet cerium dioxide has a side length of 80-300 nm, such as 80 nm, 120 nm, 160 nm, 200 nm, 240 nm, 280 nm or 300 nm, and a thickness of 2-20 nm, such as 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm or 20 nm.

[0203] Preferably, the side length of the triangular pyramid-shaped cerium dioxide is 50-180 nm, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm or 180 nm.

[0204] Preferably, the specific surface area of ​​the triangular cerium dioxide is 10-200m 2 / g, for example 10m 2 / g, 20m 2 / g, 40m 2 / g, 60m 2 / g, 80m 2 / g、100m 2 / g, 120m 2 / g, 140m 2 / g, 160m 2 / g, 180m 2 / g or 200m 2 / g, etc.

[0205] In a ninth aspect, the present invention provides an application of the triangular cerium oxide according to the eighth aspect, wherein the triangular cerium oxide is applied in semiconductor chemical mechanical polishing (CMP), optical polishing or cosmetics.

[0206] The triangular cerium dioxide provided by the present invention is suitable for any application field that can be thought of by those skilled in the art.

[0207] Compared with the prior art, the present invention has at least the following beneficial effects:

[0208] (1) The preparation method adopted by the present invention introduces a doping metal salt into a cerium salt, which is then mixed with an inorganic acid and an organic acid. The obtained product is mixed with ammonia water and an ammonium salt under hydrothermal conditions, and the pH of the obtained mixture is subjected to a sol-gel reaction under alkaline conditions within a specific range to obtain a quasi-spherical cerium dioxide sol. The quasi-spherical cerium dioxide particles are obtained by combining a post-treatment process. The particles have a regular shape, good size uniformity, and high purity and crystallinity.

[0209] (2) The preparation method adopted by the present invention introduces a doping metal salt into a cerium salt, which is then mixed with an inorganic acid and an organic acid. The obtained product is mixed with ammonia water and an ammonium salt under hydrothermal conditions, and the pH of the obtained mixture is subjected to a sol-gel reaction under weak acid conditions within a specific range to obtain a hexagonal cerium dioxide sol. The hexagonal cerium dioxide particles are obtained by combining a post-treatment process. The particles have a regular shape, good size uniformity, and high purity and crystallinity.

[0210] (3) The preparation method adopted by the present invention introduces a doped metal salt into a cerium salt, which is then mixed with an inorganic acid and an organic acid. The obtained product is mixed with ammonia water and an ammonium salt under hydrothermal conditions, and the pH of the obtained mixture is subjected to a sol-gel reaction under strong acid conditions within a specific range to obtain a triangular cerium dioxide sol. The triangular cerium dioxide particles are obtained by combining a post-treatment process. The particles have a regular shape, good size uniformity, and high purity and crystallinity. BRIEF DESCRIPTION OF THE DRAWINGS

[0211] Figure 1 This is a scanning electron microscope image of the spherical cerium dioxide of Example 1.

[0212] Figure 2 This is a scanning electron microscope image of hexagonal cerium dioxide in Example 21.

[0213] Figure 3 This is a scanning electron microscope image of the triangular cerium dioxide of Example 31.

[0214] Figure 4 This is an enlarged scanning electron microscope image of the triangular cerium dioxide of Example 31. DETAILED DESCRIPTION

[0215] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0216] Example 1

[0217] This embodiment provides a method for preparing spherical cerium dioxide, which specifically comprises the following steps:

[0218] (A) Ce(NO3)3, Pr(NO3)3, Nd(NO3)3, 3wt% nitric acid and water were mixed at 400rpm for 4h, and then 5wt% acetic acid was added and the mixture was mixed at 400rpm for 8h, wherein the molar ratio of Ce(NO3)3, Pr(NO3)3 and Nd(NO3)3 was 1000:1:1, the mass ratio of Ce(NO3)3 to water was 1:150, and the volume ratio of nitric acid, acetic acid and water was 2:1:240, to obtain a first mixture.

[0219] (B) Under hydrothermal conditions of a temperature of 95°C and a pressure of 5 MPa, the first mixture obtained in step (A) was mixed with ammonia water and ammonium nitrate in a mass ratio of 4:2 in a hydrothermal reactor for 0.5 h, the concentration of ammonia water was 1.5 wt%, and a second mixture with a pH of 8.9 was obtained. Then, the pH of the mixture was maintained at 8.9, and the temperature in the hydrothermal reactor was maintained at 150°C for sol-gel reaction. The sol-gel reaction was also accompanied by stirring at a speed of 300 rpm, until a spherical cerium dioxide sol with a solid content of 30 wt% was obtained in the reactor.

[0220] (C) The spherical cerium dioxide sol obtained in step (B) is concentrated at a pressure of 5 MPa and a temperature of 120° C. until a sol with a solid content of 95 wt% is obtained, and the obtained sol is centrifuged at a speed of 3000 rpm to obtain a solid product, and then the obtained solid product is dried at 300° C. for 8 hours, and after deagglomeration by air grinding, a spherical cerium dioxide is obtained, and the specific surface area of ​​the obtained spherical cerium dioxide is 214 m 2 / g.

[0221] Example 2

[0222] This embodiment provides a method for preparing spherical cerium dioxide, which specifically comprises the following steps:

[0223] (A) CeCl3, PrCl3, NdCl3, 3wt% nitric acid and water are mixed at 200rpm for 5h, and then 1wt% butyric acid is added and mixed at 200rpm for 15h, wherein the molar ratio of CeCl3, PrCl3 and NdCl3 is 5000:5:1, the mass ratio of CeCl3 to water is 1:100, and the volume ratio of nitric acid, butyric acid and water is 1.5:1:220, to obtain a first mixture.

[0224] (B) Under hydrothermal conditions of a temperature of 100° C. and a pressure of 10 MPa, the first mixture obtained in step (A) is mixed with ammonia water and ammonium chloride in a mass ratio of 3.5:2 in a hydrothermal reactor for 2 h, wherein the concentration of the ammonia water is 2 wt %, to obtain a second mixture with a pH of 8. Then, the pH of the mixture is maintained at 8, and the temperature in the hydrothermal reactor is maintained at 160° C. to carry out a sol-gel reaction, and the sol-gel reaction is also accompanied by stirring at a speed of 50 rpm, until a spherical cerium dioxide sol with a solid content of 20 wt % is obtained in the reactor.

[0225] (C) The spherical cerium dioxide sol obtained in step (B) is concentrated at a pressure of 10 MPa and a temperature of 180°C until a sol with a solid content of 85 wt% is obtained, and the obtained sol is centrifuged at a rotation speed of 4500 rpm to obtain a solid product. Then, the obtained solid product is dried at 500°C for 6 hours, and after deagglomeration by gas phase injection, spherical cerium dioxide is obtained.

[0226] Example 3

[0227] This embodiment provides a method for preparing spherical cerium dioxide, which specifically comprises the following steps:

[0228] (A) Ce(SO4)3, Pr(SO4)3, Nd(SO4)3, 3wt% nitric acid and water were mixed at 600rpm for 4h, and then 3wt% acetic acid was added and mixed at 600rpm for 16h, wherein the molar ratio of Ce(SO4)3, Pr(SO4)3 and Nd(SO4)3 was 3000:2:1, the mass ratio of Ce(SO4)3 to water was 1:200, and the volume ratio of nitric acid, acetic acid and water was 2.5:1:280, to obtain a first mixture.

[0229] (B) Under hydrothermal conditions of a temperature of 30° C. and a pressure of 0.5 MPa, the first mixture obtained in step (A) is mixed with ammonia water and ammonium sulfate in a mass ratio of 4.5:2 in a hydrothermal reactor for 5 hours, the concentration of ammonia water is 5 wt %, and a second mixture with a pH of 10 is obtained. Then, the pH of the mixture is maintained at 10, and the temperature in the hydrothermal reactor is maintained at 160° C. to carry out a sol-gel reaction, and the sol-gel reaction is also accompanied by stirring at a speed of 100 rpm, until a spherical cerium dioxide sol with a solid content of 40 wt % is obtained in the reactor.

[0230] (C) The spherical cerium dioxide sol obtained in step (B) is concentrated at a pressure of 8 MPa and a temperature of 150° C. until a sol with a solid content of 70 wt% is obtained, and the obtained sol is centrifuged at a rotation speed of 5000 rpm to obtain a solid product. Then, the obtained solid product is dried at 1000° C. for 12 h, and after deagglomeration by convection jet, spherical cerium dioxide is obtained.

[0231] Example 4

[0232] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the molar ratio of Ce(NO3)3, Pr(NO3)3 and Nd(NO3)3 in step (A) is 50:1:1. The rest of the contents are the same as those in embodiment 1.

[0233] Example 5

[0234] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the molar ratio of Ce(NO3)3, Pr(NO3)3 and Nd(NO3)3 in step (A) is 12000:1:1. The rest of the contents are the same as those in embodiment 1.

[0235] Example 6

[0236] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, step (A) is to mix nitric acid and organic acid with Ce(NO3)3, Pr(NO3)3, Nd(NO3)3 and water at a rotation speed of 400 rpm for 12 hours. The rest of the contents are the same as those in embodiment 1.

[0237] Example 7

[0238] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the volume ratio of nitric acid, acetic acid and water in step (A) is 0.5:1:120. The rest of the contents are the same as those in embodiment 1.

[0239] Example 8

[0240] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the volume ratio of nitric acid, acetic acid and water in step (A) is 4:1:400. The rest of the contents are the same as those in embodiment 1.

[0241] Example 9

[0242] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the mixing speed in step (A) is 100 rpm. The rest of the contents are the same as those in embodiment 1.

[0243] Example 10

[0244] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the mixing speed in step (A) is 700 rpm. The rest of the contents are the same as those in embodiment 1.

[0245] Embodiment 11

[0246] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the mass ratio of ammonia water to ammonium nitrate in step (B) is 2:2. The rest of the contents are the same as those in embodiment 1.

[0247] Example 12

[0248] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the mass ratio of ammonia water to ammonium nitrate in step (B) is 6:2. The rest of the contents are the same as those in embodiment 1.

[0249] Example 13

[0250] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the sol-gel reaction in step (B) is not stirred. The rest of the contents are the same as those in embodiment 1.

[0251] Embodiment 14

[0252] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the stirring speed of the sol-gel reaction in step (B) is 600 rpm. The rest of the contents are the same as those in embodiment 1.

[0253] Embodiment 15

[0254] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the solid content of the concentrated product in step (C) is 50 wt %. The rest of the contents are the same as those in embodiment 1.

[0255] Comparative Example 1

[0256] The difference between this comparative example and Example 1 is that in the preparation method provided in this comparative example, the addition of organic acid acetic acid in step (A) is omitted. The rest of the contents are the same as those in Example 1.

[0257] Comparative Example 2

[0258] The difference between this comparative example and Example 1 is that in the preparation method provided in this comparative example, the addition of ammonium nitrate in step (B) is omitted. The rest of the contents are the same as those in Example 1.

[0259] Comparative Example 3

[0260] The difference between this comparative example and Example 1 is that in the preparation method provided in this comparative example, the pH of the second mixture in step (B) is maintained at 7. The rest of the contents are the same as those in Example 1.

[0261] Comparative Example 4

[0262] The difference between this comparative example and Example 1 is that in the preparation method provided in this comparative example, the pH of the second mixture in step (B) is maintained at 11. The rest of the contents are the same as those in Example 1.

[0263] The final products obtained from the above embodiments and comparative examples were tested to detect the particle size, crystallinity, and impurity content of the obtained products, and the particle size dispersion was calculated by the particle size of the particles. The calculation formula is: dispersion = (D90-D10) / D50. The impurity content in the obtained products was tested by inductively coupled plasma optical emission spectrometry (ICP-OES) to measure the content of the remaining elements in the products except cerium dioxide nanoparticles. The results are shown in Table 1.

[0264] Table 1

[0265] Particle size D50(nm) Particle size dispersion Impurity content (ppm) Crystallinity(%) Example 1 120 1.53 <1 99 Example 2 100 2.31 <1 98 Example 3 140 2.05 <1 99 Example 4 300 5.67 <100 72 Example 5 150 4.67 <100 89 Example 6 350 6.67 <100 85 Example 7 280 9.78 <1000 69 Example 8 200 10.91 <1000 66 Example 9 450 11.21 <100 71 Example 10 220 6.72 <1000 83 Embodiment 11 780 11.87 <10000 42 Example 12 250 6.97 <10 73 Example 13 - - <100 0 Embodiment 14 200 20.87 <100 91 Embodiment 15 130 1.67 <10 96 Comparative Example 1 - - - - Comparative Example 2 330 10.47 <10 54 Comparative Example 3 280 6.67 <10 67 Comparative Example 4 330 11.94 <10 84

[0266] From Table 1 we can see that:

[0267] (1) It can be seen from Examples 1 to 3 that the preparation method adopted by the present invention introduces a doping metal salt into a cerium salt, which is then mixed with an inorganic acid and an organic acid. The obtained product is mixed with ammonia water and an ammonium salt under hydrothermal conditions, and the pH of the obtained mixture is subjected to a sol-gel reaction under alkaline conditions within a specific range to obtain a quasi-spherical cerium dioxide sol. Combined with a post-treatment process, quasi-spherical cerium dioxide particles are obtained, and the particles have a regular shape, good size uniformity, and high purity and crystallinity.

[0268] Figure 1 The scanning electron microscope image of the spherical cerium dioxide prepared in Example 1 is given. It can be seen from the image that the cerium dioxide prepared by the present invention using specific processes and parameters is spherical, and the obtained spherical cerium dioxide has a regular morphology and uniform particle size.

[0269] (2) By comparing Example 1 with Examples 4-5, it can be seen that if the molar ratio of cerium ions in the cerium salt to the doped metal ions in the doped metal salt is too low, and the cerium ion content is too low, the particles cannot be formed and spherical cerium dioxide with excellent morphology and performance cannot be obtained; if the molar ratio of the two is too high and the content of the doped metal ions is too low, the morphology of cerium dioxide will be affected, and the crystallinity of the obtained product will be poor.

[0270] (3) By comparing Example 1 and Example 6, it can be seen that if the preparation process of the present invention is changed from adding the inorganic acid first and then the organic acid, and the inorganic acid and the organic acid are mixed at the same time, the particle size dispersion of the obtained cerium dioxide will be high, the particle size uniformity will be poor, and the purity and crystallinity of the product will be affected.

[0271] (4) By comparing Example 1 with Examples 7-8, it can be seen that in the preparation of quasi-spherical cerium dioxide in the present invention, if the volume ratio of the inorganic acid to the organic acid is too low, and the amount of the inorganic acid added is relatively too small, the reaction rate will slow down, resulting in incomplete reaction for preparing the quasi-spherical cerium dioxide, thereby affecting the preparation of the quasi-spherical cerium dioxide and causing the performance of the resulting product to deteriorate; if the volume ratio of the inorganic acid to the organic acid is too high, and the amount of the organic acid added is relatively too small, the content of the quasi-spherical cerium dioxide in the final product will be reduced, the product purity will be low, and the particle uniformity of the quasi-spherical cerium dioxide will also deteriorate.

[0272] (5) By comparing Example 1 with Examples 9-10, it can be seen that if the mixing speed in step (A) of the present invention is too low, the uniformity of the raw material mixing is poor, and the uniform morphology of the spherical cerium dioxide obtained is poor, and the consistency of the particle size is poor, thereby affecting the product purity and crystallinity; if the mixing speed in step (A) is too high, foam and microbubbles are likely to occur during the mixing process, affecting the reaction of the spherical cerium dioxide, thereby affecting the morphology and performance of the obtained particles.

[0273] (6) By comparing Example 1 with Examples 11-12, it can be seen that if the mass ratio of ammonia water to ammonium salt is too low and the amount of ammonia water added is relatively too small, the reaction for preparing quasi-spherical cerium dioxide will be incomplete, and the purity and crystallinity of the obtained quasi-spherical cerium dioxide will deteriorate; if the mass ratio of ammonia water to ammonium salt is too high and the amount of ammonium salt added is relatively too small, the reaction rate for preparing quasi-spherical cerium dioxide will be reduced, affecting the production efficiency and the morphology of the subsequently obtained cerium dioxide.

[0274] (7) By comparing Example 1 with Examples 13-14, it can be seen that if the stirring process of the sol-gel reaction process is omitted in the present invention, the particles cannot be formed; if the stirring speed during the sol-gel reaction process is too high, the uniformity of the spherical cerium dioxide particles decreases.

[0275] (8) By comparing Example 1 and Example 15, it can be seen that if the solid content of the concentrated product of the present invention is too low, although it has little effect on the particle size, particle size dispersion, purity and crystallinity of the product, it will cause the content of the obtained spherical cerium dioxide to decrease.

[0276] (9) By comparing Example 1 with Comparative Example 1, it can be seen that if the addition of organic acid is omitted in the present invention, the internal reaction cannot occur smoothly and a highly active intermediate cannot be obtained, thereby affecting the preparation of spherical cerium dioxide, so that cerium dioxide cannot be prepared.

[0277] (10) By comparing Example 1 and Comparative Example 2, it can be seen that if the addition of ammonium salt is omitted in the present invention, the reaction efficiency will be reduced, the reaction will be insufficient, and the shape of the particles will be affected.

[0278] (11) By comparing Example 1 with Comparative Examples 3-4, it can be seen that if the pH of the present invention is adjusted outside the range of 8-10, or the pH is too low or too high, it will affect the morphology of cerium dioxide, resulting in irregular morphology of the generated cerium dioxide particles, which cannot be formed into a regular spherical morphology, thereby causing the crystallinity of the particles to decrease.

[0279] In summary, the preparation method provided by the present invention is to mix cerium salt and doped metal salt with inorganic acid and organic acid in a solvent to obtain a composite cerium salt and a composite doped metal salt containing both inorganic acid radicals and organic acid radicals, and then under hydrothermal conditions, the composite cerium salt and the composite doped metal salt react with ammonia and ammonium salt to obtain a highly active intermediate, combined with precise control of the pH value in the reaction solution in the range of 8-10, and a sol-gel reaction is performed under alkaline conditions of a specific pH value, and the highly active intermediate can stably crystallize to form a specific shape of cerium dioxide seeds, and the seeds maintain a specific shape and continue to grow uniformly to form a spherical crystal nucleus with uniform size and regular morphology, and the crystal nucleus is gelled to obtain a spherical cerium dioxide sol, and the obtained sol is subjected to a post-treatment process to finally obtain a spherical cerium dioxide particle with high purity and crystallinity. The present invention also introduces a specific praseodymium salt and / or a neodymium salt as a doped metal salt in the cerium salt to promote the regulation of the morphology of the product and to improve the crystallinity of the product, thereby facilitating the polishing effect of the obtained material. The preparation method adopted by the present invention has short reaction time, simple operation and easy mass production. The prepared cerium dioxide has a quasi-spherical morphology with regular shape, uniform particles, good crystallinity and high purity. It can be widely used in semiconductor chemical mechanical polishing (CMP), high-end optical polishing or cosmetics and other fields.

[0280] Example 16

[0281] This embodiment provides a method for preparing hexagonal cerium dioxide, which specifically includes the following steps:

[0282] (Ⅰ) Ce(NO3)3, Pr(NO3)3, Nd(NO3)3, 3wt% acetic acid and water are mixed at 2000rpm for 4h, and then 7wt% nitric acid is added and the mixture is mixed at 2000rpm for 20h, wherein the molar ratio of Ce(NO3)3, Pr(NO3)3 and Nd(NO3)3 is 10000:1:1, the mass ratio of Ce(NO3)3 to water is 1:150, and the volume ratio of nitric acid, acetic acid and water is 3:1:280, to obtain a first mixture.

[0283] (II) Under hydrothermal conditions of a temperature of 95°C and a pressure of 5 MPa, the first mixture obtained in step (I) and ammonium nitrate are placed in a hydrothermal reactor for mixing for 2 hours, and then ammonia water is added for mixing for 0.5 hours, the mass ratio of ammonia water to ammonium nitrate is 5:2, and the concentration of ammonia water is 20wt%, to obtain a second mixture with a pH of 5. Then, the pH of the mixture is maintained at 5, and the temperature in the hydrothermal reactor is maintained at 150°C for sol-gel reaction. The sol-gel reaction is also accompanied by stirring at a speed of 300 rpm until a hexagonal cerium dioxide sol with a solid content of 30wt% is obtained in the reactor.

[0284] (III) The hexagonal cerium dioxide sol obtained in step (II) is concentrated at a pressure of 5 MPa and a temperature of 120° C. until a sol with a solid content of 95 wt% is obtained, and the obtained sol is centrifuged at a speed of 3400 rpm to obtain a solid product, and then the obtained solid product is dried at 300° C. for 8 hours, and after deagglomeration by air grinding, hexagonal cerium dioxide is obtained. The specific surface area of ​​the obtained hexagonal cerium dioxide is 198 m 2 / g.

[0285] Embodiment 17

[0286] This embodiment provides a method for preparing hexagonal cerium dioxide, which specifically includes the following steps:

[0287] (I) CeCl3, PrCl3, NdCl3, 6wt% butyric acid and water are mixed at 1000rpm for 4.5h, and then 8wt% nitric acid is added and the mixture is mixed at 1000rpm for 20.5h, wherein the molar ratio of CeCl3, PrCl3 and NdCl3 is 50000:5:1, the mass ratio of CeCl3 to water is 1:100, and the volume ratio of nitric acid, butyric acid and water is 4:1:300, to obtain a first mixture.

[0288] (II) Under hydrothermal conditions of a temperature of 40°C and a pressure of 1 MPa, the first mixture obtained in step (I) and ammonium chloride are placed in a hydrothermal reactor for mixing for 3 hours, and then aqueous ammonia is added for mixing for 3 hours, the mass ratio of aqueous ammonia to ammonium chloride is 6:2, and the concentration of aqueous ammonia is 5wt%, to obtain a second mixture with a pH of 3.5. Then, the pH of the mixture is maintained at 3.5, and the temperature in the hydrothermal reactor is maintained at 50°C for sol-gel reaction. The sol-gel reaction is also accompanied by stirring at a speed of 200 rpm until a hexagonal cerium dioxide sol with a solid content of 40wt% is obtained in the reactor.

[0289] (III) The hexagonal cerium dioxide sol obtained in step (II) is concentrated at a pressure of 10 MPa and a temperature of 180° C. until a sol with a solid content of 85 wt% is obtained, and the obtained sol is centrifuged at a speed of 2000 rpm to obtain a solid product. Then, the obtained solid product is dried at 500° C. for 6 h, and deagglomerated by gas phase injection to obtain hexagonal cerium dioxide.

[0290] Embodiment 18

[0291] This embodiment provides a method for preparing hexagonal cerium dioxide, which specifically includes the following steps:

[0292] (Ⅰ) Ce(SO4)3, Pr(SO4)3, Nd(SO4)3, 3wt% acetic acid and water are mixed at 15000rpm for 4h, and then 2wt% nitric acid is added and the mixture is mixed at 15000rpm for 16h, wherein the molar ratio of Ce(SO4)3, Pr(SO4)3 and Nd(SO4)3 is 1500:2:1, the mass ratio of Ce(SO4)3 to water is 1:200, and the volume ratio of nitric acid, acetic acid and water is 2.8:1:240, to obtain a first mixture.

[0293] (II) Under hydrothermal conditions of a temperature of 100° C. and a pressure of 10 MPa, the first mixture obtained in step (I) and ammonium sulfate are placed in a hydrothermal reactor for mixing for 0.5 h, and then aqueous ammonia is added for mixing for 0.5 h, the mass ratio of aqueous ammonia to ammonium sulfate is 4.8:2, and the concentration of aqueous ammonia is 35 wt %, to obtain a second mixture with a pH of 6. Then, the pH of the mixture is maintained at 6, and the temperature in the hydrothermal reactor is maintained at 160° C. for sol-gel reaction, and the sol-gel reaction is also accompanied by stirring at a speed of 1000 rpm until a hexagonal cerium dioxide sol with a solid content of 20 wt % is obtained in the reactor.

[0294] (III) The hexagonal cerium dioxide sol obtained in step (II) is concentrated at a pressure of 8 MPa and a temperature of 150°C until a sol with a solid content of 70 wt% is obtained, and the obtained sol is centrifuged at a speed of 4000 rpm to obtain a solid product. Then, the solid product is dried at 1000°C for 12 h, and deagglomerated by convection jet to obtain hexagonal cerium dioxide.

[0295] Embodiment 19

[0296] The difference between this example and Example 16 is that in the preparation method provided in this example, the molar ratio of Ce(NO3)3, Pr(NO3)3 and Nd(NO3)3 in step (I) is 400:1:1. The rest of the contents are the same as those in Example 16.

[0297] Embodiment 20

[0298] The difference between this embodiment and embodiment 16 is that in the preparation method provided in this embodiment, the molar ratio of Ce(NO3)3, Pr(NO3)3 and Nd(NO3)3 in step (I) is 110000:1:1. The rest of the contents are the same as those in embodiment 16.

[0299] Embodiment 21

[0300] The difference between this example and Example 16 is that in the preparation method provided in this example, step (I) is to mix nitric acid and organic acid with Ce(NO3)3, Pr(NO3)3, Nd(NO3)3 and water at a rotation speed of 2000 rpm for 24 hours. The rest of the contents are the same as Example 16.

[0301] Embodiment 22

[0302] The only difference between this example and Example 16 is that in the preparation method provided in this example, the volume ratio of nitric acid, acetic acid and water in step (I) is 2:1:210. The rest of the contents are the same as those in Example 16.

[0303] Embodiment 23

[0304] The only difference between this example and Example 16 is that in the preparation method provided in this example, the volume ratio of nitric acid, acetic acid and water in step (I) is 5:1:420. The rest of the contents are the same as those in Example 16.

[0305] Embodiment 24

[0306] The difference between this embodiment and embodiment 16 is that in the preparation method provided in this embodiment, the mixing speed in step (I) is 900 rpm. The rest of the contents are the same as those in embodiment 16.

[0307] Embodiment 25

[0308] The difference between this embodiment and embodiment 16 is that in the preparation method provided in this embodiment, the mixing speed in step (I) is 16000 rpm. The rest of the contents are the same as those in embodiment 16.

[0309] Embodiment 26

[0310] The difference between this embodiment and embodiment 16 is that in the preparation method provided in this embodiment, the mass ratio of ammonia water to ammonium nitrate in step (II) is 4:2. The rest of the contents are the same as those in embodiment 16.

[0311] Embodiment 27

[0312] The difference between this embodiment and embodiment 16 is that in the preparation method provided in this embodiment, the mass ratio of ammonia water to ammonium nitrate in step (II) is 7:2. The rest of the contents are the same as those in embodiment 16.

[0313] Embodiment 28

[0314] The difference between this embodiment and embodiment 1 is that in the preparation method provided in this embodiment, the stirring process is omitted during the sol-gel reaction of step (II). The rest of the contents are the same as those of embodiment 1.

[0315] Embodiment 29

[0316] The difference between this embodiment and embodiment 16 is that in the preparation method provided in this embodiment, the stirring speed of the sol-gel reaction in step (II) is 2200 rpm. The rest of the contents are the same as those in embodiment 16.

[0317] Embodiment 30

[0318] The difference between this example and Example 16 is that in the preparation method provided in this example, the solid content of the concentrated product in step (III) is 50 wt %. The rest of the contents are the same as those in Example 16.

[0319] Comparative Example 5

[0320] The difference between this comparative example and Example 16 is that in the preparation method provided in this comparative example, the addition of organic acid in step (I) is omitted. The rest of the contents are the same as those in Example 16.

[0321] Comparative Example 6

[0322] The difference between this comparative example and Example 16 is that in the preparation method provided in this comparative example, the addition of ammonium nitrate in step (II) is omitted. The rest of the contents are the same as those in Example 16.

[0323] Comparative Example 7

[0324] The difference between this comparative example and Example 16 is that in the preparation method provided in this comparative example, the pH in step (III) is adjusted to 2. The rest of the contents are the same as those in Example 1.

[0325] Comparative Example 8

[0326] The difference between this comparative example and Example 16 is that in the preparation method provided in this example, the pH value in step (III) is adjusted to 7. The rest of the contents are the same as those in Example 16.

[0327] The final products obtained from the above embodiments and comparative examples were tested to detect the particle size, crystallinity, and impurity content of the obtained products, and the particle size dispersion was calculated by the particle size of the particles. The calculation formula is: dispersion = (D90-D10) / D50. The impurity content in the obtained product was tested by inductively coupled plasma optical emission spectrometry (ICP-OES) to test the content of the remaining elements in the product except cerium dioxide nanoparticles. The results are shown in Table 2.

[0328] Table 2

[0329] Particle size D50(nm) Particle size dispersion Impurity content (ppm) Crystallinity(%) Example 16 180 1.33 <1 100 Embodiment 17 120 2.07 <1 99 Embodiment 18 200 1.67 <1 99 Embodiment 19 380 4.29 <1000 77 Embodiment 20 260 7.28 <100 93 Embodiment 21 430 5.37 <100 67 Embodiment 22 360 7.67 <100 39 Embodiment 23 560 6.67 <100 53 Embodiment 24 780 5.73 <100 72 Embodiment 25 230 13.74 <100 64 Embodiment 26 370 11.54 <10000 68 Embodiment 27 200 5.69 <10000 76 Embodiment 28 1000 10.67 <100 29 Embodiment 29 220 15.77 <100 76 Embodiment 30 180 2.17 <100 88 Comparative Example 5 - - - - Comparative Example 6 230 7.67 <10 68 Comparative Example 7 235 5.13 <10 44 Comparative Example 8 195 6.87 <10 75

[0330] From Table 2 we can see that:

[0331] (1) It can be seen from Examples 16 to 18 that the preparation method adopted by the present invention introduces a doping metal salt into a cerium salt, which is then mixed with an inorganic acid and an organic acid. The obtained product is mixed with ammonia water and an ammonium salt under hydrothermal conditions, and the pH of the obtained mixture is subjected to a sol-gel reaction under weak acid conditions within a specific range to obtain a hexagonal cerium dioxide sol, which is then combined with a post-treatment process to obtain hexagonal cerium dioxide particles, which have regular shape, good size uniformity, and high purity and crystallinity.

[0332] Figure 2 The scanning electron microscope image of the hexagonal cerium dioxide obtained in Example 16 is given. It can be seen from the figure that the particles present a flaky hexagonal structure, and the particles have a regular morphology and uniform size. In addition, the average side length of the hexagon obtained in Example 16 is 120nm and the average thickness is 5nm.

[0333] (2) By comparing Example 16 with Examples 19-20, it can be seen that if the molar ratio of cerium ions in the cerium salt to the doped metal ions in the doped metal salt is too low, it will affect the uniformity and morphological consistency of the hexagonal cerium dioxide particles, as well as the purity and crystallinity of the obtained particles; if the molar ratio of the two is too high, it will affect the morphology and polishing performance of the hexagonal cerium dioxide particles.

[0334] (3) By comparing Example 16 and Example 21, it can be seen that if the preparation process of the present invention is changed from adding the inorganic acid first and then the organic acid, and the inorganic acid and the organic acid are mixed at the same time, it will result in poor uniformity of the particle size of the hexagonal cerium dioxide particles finally prepared and a decrease in crystallinity.

[0335] (4) By comparing Example 16 with Examples 22-23, it can be seen that in the preparation of hexagonal cerium dioxide in the present invention, if the volume ratio of the inorganic acid to the organic acid is too low, and the amount of the inorganic acid added is relatively too small, the reaction for preparing hexagonal cerium dioxide will be incomplete, affecting the preparation of hexagonal cerium dioxide and thus affecting the performance of the hexagonal cerium dioxide product; if the volume ratio of the inorganic acid to the organic acid is too high, and the amount of the organic acid added is relatively too small, the hexagonal cerium dioxide content in the final product is reduced, the product purity and crystallinity are low, and the particle size uniformity of the hexagonal cerium dioxide is affected.

[0336] (5) By comparing Example 16 with Examples 24-25, it can be seen that if the mixing speed in step (I) of the present invention is too low, it will affect the morphological identity and size uniformity of the hexagonal cerium dioxide, and cause the performance of the particles to deteriorate; if the mixing speed in step (I) is too high, a large number of microbubbles will be generated, affecting the reaction process of preparing hexagonal cerium dioxide, resulting in poor particle size uniformity of the hexagonal cerium dioxide and low crystallinity of the particles.

[0337] (6) By comparing Example 16 with Examples 26-27, it can be seen that if the mass ratio of ammonia water to ammonium salt in the preparation of hexagonal cerium dioxide in the present invention is too low or too high, it will lead to the reaction progress of the hexagonal cerium dioxide preparation process, resulting in incomplete reaction for preparing hexagonal cerium dioxide, thereby affecting the morphology, purity and crystallinity of cerium dioxide.

[0338] (7) By comparing Example 16 with Examples 28-29, it can be seen that if the stirring process of the sol-gel reaction process is omitted in the present invention, the reaction will be incomplete, and gel will occur to produce huge particles, resulting in extremely low crystallinity of the final particles; if the stirring speed during the sol-gel reaction is too high, microbubbles will be generated to affect the reaction, thereby affecting the morphology and performance of the hexagonal cerium dioxide.

[0339] (8) By comparing Example 16 and Example 30, it can be seen that if the solid content of the concentrated product of the present invention is too low, although it has little effect on the particle size, particle size dispersion, purity and crystallinity of cerium dioxide, it will cause the content of hexagonal cerium dioxide obtained to decrease.

[0340] (9) By comparing Example 16 with Comparative Example 5, it can be seen that if the addition of organic acid is omitted in the present invention, the internal reaction will not proceed smoothly, and the composite metal salt and highly active intermediates cannot be obtained, thereby affecting the preparation of hexagonal cerium dioxide, so that cerium dioxide cannot be prepared.

[0341] (10) By comparing Example 16 with Comparative Example 6, it can be seen that if the addition of ammonium salt is omitted in the present invention, the reaction efficiency will be reduced, the reaction will be insufficient, and the shape of the particles will be affected.

[0342] (11) By comparing Example 16 with Comparative Examples 7-8, it can be seen that if the pH of the present invention is adjusted outside the range of 3.5-6, or the pH is too low or too high, it will affect the morphology of cerium dioxide, resulting in irregular morphology of the generated cerium dioxide particles, which cannot be formed into a regular hexagonal morphology, thereby affecting the preparation content of hexagonal cerium dioxide, and further resulting in a decrease in the crystallinity of the particles.

[0343] In summary, the preparation method provided by the present invention introduces specific praseodymium salts and / or neodymium salts as doping metal salts into cerium salts, promotes the regulation of product morphology in subsequent reactions and can improve the crystallinity of the obtained product, and then mixes the cerium salt and the doping metal salt with an inorganic acid and an organic acid in a solvent to obtain a composite cerium salt and a composite doping metal salt containing both inorganic acid radicals and organic acid radicals, and then under hydrothermal conditions, the composite cerium salt and the composite doping metal salt can react with ammonia water and an ammonium salt to obtain a highly active intermediate, and the pH value in the reaction solution is precisely controlled to be within the range of 3.5-6, and a sol-gel reaction is carried out under weakly acidic conditions at a specific pH value, and the highly active intermediate can stably crystallize to form a cerium dioxide seed crystal of a specific shape, and the seed crystal maintains a specific shape and continues to grow uniformly to form a hexagonal crystal nucleus with uniform size and regular morphology, and the crystal nucleus is gelled to obtain a hexagonal cerium dioxide sol, and the obtained sol is then subjected to a post-treatment process to finally obtain hexagonal cerium dioxide particles with high purity and crystallinity. The preparation method adopted by the present invention has short reaction time, simple operation and easy mass production. The prepared cerium dioxide has a hexagonal morphology with regular shape, good particle uniformity, high crystallinity and purity, and can be widely used in semiconductor CMP polishing, high-end optical polishing or cosmetics and other fields.

[0344] Embodiment 31

[0345] This embodiment provides a method for preparing triangular cerium dioxide, which specifically comprises the following steps:

[0346] S1. Mix Ce(NO3)3, Pr(NO3)3, Nd(NO3)3, 10wt% acetic acid and water at 1500rpm for 5h, then add 8wt% nitric acid and continue mixing at 1500rpm for 19h, wherein the molar ratio of Ce(NO3)3, Pr(NO3)3 and Nd(NO3)3 is 80000:1:1, the mass ratio of Ce(NO3)3 to water is 1:150, and the volume ratio of nitric acid, acetic acid and water is 8:3:400, to obtain a first mixture.

[0347] S2. Under hydrothermal conditions of a temperature of 95°C and a pressure of 5 MPa, the first mixture obtained in step S1 and ammonia water are placed in a hydrothermal reactor for mixing for 2 hours, and then ammonium nitrate is added for mixing for 1 hour. The mass ratio of ammonia water to ammonium nitrate is 10:2, and the concentration of ammonia water is 5wt%. A second mixture with a pH of 2 is obtained. Then, the pH of the mixture is maintained at 2, and the temperature in the hydrothermal reactor is maintained at 150°C for sol-gel reaction. The sol-gel reaction is also accompanied by stirring at a speed of 2000 rpm until a triangular cerium dioxide sol with a solid content of 30wt% is obtained in the reactor.

[0348] S3. The triangular cerium dioxide sol obtained in step S2 is concentrated at a pressure of 5 MPa and a temperature of 120° C. until a sol with a solid content of 95 wt% is obtained, and the obtained sol is centrifuged at a speed of 3500 rpm to obtain a solid product, and then the obtained solid product is dried at 300° C. for 8 hours, and after deagglomeration by air grinding, triangular cerium dioxide is obtained. The specific surface area of ​​the obtained triangular cerium dioxide is 151 m 2 / g.

[0349] Embodiment 32

[0350] This embodiment provides a method for preparing triangular cerium dioxide, which specifically comprises the following steps:

[0351] S1. CeCl3, PrCl3, NdCl3, 12wt% butyric acid and water are mixed at a rotation speed of 1000rpm for 3h, and then 12wt% nitric acid is added and the mixture is mixed at a rotation speed of 1000rpm for 20h, wherein the molar ratio of CeCl3, PrCl3 and NdCl3 is 500000:5:1, the mass ratio of CeCl3 to water is 1:100, and the volume ratio of nitric acid, butyric acid and water is 6:3:420 to obtain a first mixture.

[0352] S2. Under hydrothermal conditions of a temperature of 50°C and a pressure of 1 MPa, the first mixture obtained in step S1 and ammonia water are placed in a hydrothermal reactor for mixing for 3 hours, and then ammonium chloride is added for mixing for 3 hours. The mass ratio of ammonia water to ammonium chloride is 8:2, and the concentration of ammonia water is 20wt%. A second mixture with a pH of 3 is obtained. Then, the pH of the mixture is maintained at 3, and the temperature in the hydrothermal reactor is maintained at 50°C for sol-gel reaction. The sol-gel reaction is also accompanied by stirring at a speed of 300rpm until a triangular cerium dioxide sol with a solid content of 20wt% is obtained in the reactor.

[0353] S3. The triangular cerium dioxide sol obtained in step S2 is concentrated at a pressure of 10 MPa and a temperature of 180°C until a sol with a solid content of 85 wt% is obtained, and the obtained sol is centrifuged at a rotation speed of 2300 rpm to obtain a solid product. Then, the obtained solid product is dried at 500°C for 6 hours, and after deagglomeration by gas phase injection, triangular cerium dioxide is obtained.

[0354] Embodiment 33

[0355] This embodiment provides a method for preparing triangular cerium dioxide, which specifically comprises the following steps:

[0356] S1. Mix Ce(SO4)3, Pr(SO4)3, Nd(SO4)3, 8wt% acetic acid and water at 2000rpm for 5h, then add 13wt% nitric acid and continue mixing at 2000rpm for 20h, wherein the molar ratio of Ce(SO4)3, Pr(SO4)3 and Nd(SO4)3 is 3000:2:1, the mass ratio of Ce(SO4)3 to water is 1:200, and the volume ratio of nitric acid, acetic acid and water is 10:3:350, to obtain a first mixture.

[0357] S2. Under hydrothermal conditions of a temperature of 100°C and a pressure of 10 MPa, the first mixture obtained in step S1 and ammonia water are placed in a hydrothermal reactor for mixing for 0.5 h, and then ammonium sulfate is added for mixing for 0.5 h. The mass ratio of ammonia water to ammonium sulfate is 12:2, and the concentration of ammonia water is 20wt%. A second mixture with a pH of 1 is obtained. Then, the pH of the mixture is maintained at 1, and the temperature in the hydrothermal reactor is maintained at 160°C for sol-gel reaction. The sol-gel reaction is also accompanied by stirring at a speed of 3000 rpm until a triangular cerium dioxide sol with a solid content of 40wt% is obtained in the reactor.

[0358] S3. The triangular cerium dioxide sol obtained in step S2 is concentrated at a pressure of 8 MPa and a temperature of 150°C until a sol with a solid content of 70 wt% is obtained, and the obtained sol is centrifuged at a rotation speed of 3000 rpm to obtain a solid product. Then, the obtained solid product is dried at 1000°C for 12 hours, and after deagglomeration by convection jet, triangular cerium dioxide is obtained.

[0359] Embodiment 34

[0360] The difference between this embodiment and embodiment 31 is that in the preparation method of triangular cerium dioxide provided in this embodiment, the molar ratio of Ce(NO3)3, Pr(NO3)3 and Nd(NO3)3 in step S1 is 800:1:1. The rest of the contents are the same as those in embodiment 31.

[0361] Embodiment 35

[0362] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, the molar ratio of Ce(NO3)3, Pr(NO3)3 and Nd(NO3)3 in step S1 is 1100000:1:1. The rest of the contents are the same as those in embodiment 31.

[0363] Embodiment 36

[0364] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, step S1 is to mix nitric acid and organic acid with Ce(NO3)3, Pr(NO3)3, Nd(NO3)3 and water at a speed of 1500 rpm for 24 hours. The rest of the contents are the same as those in embodiment 31.

[0365] Embodiment 37

[0366] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, the volume ratio of nitric acid, acetic acid and water in step S1 is 5:3:290. The rest of the contents are the same as those in embodiment 31.

[0367] Embodiment 38

[0368] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, the volume ratio of nitric acid, acetic acid and water in step S1 is 12:3:550. The rest of the contents are the same as those in embodiment 31.

[0369] Embodiment 39

[0370] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, the mixing speed in step S1 is 900 rpm. The rest of the contents are the same as those in embodiment 31.

[0371] Embodiment 40

[0372] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, the mixing speed in step S1 is 2200 rpm. The rest of the contents are the same as those in embodiment 31.

[0373] Embodiment 41

[0374] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, the mass ratio of ammonia water to ammonium nitrate in step S2 is 6:2. The rest of the contents are the same as those in embodiment 31.

[0375] Embodiment 42

[0376] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, the mass ratio of ammonia water to ammonium nitrate in step S2 is 14:2. The rest of the contents are the same as those in embodiment 31.

[0377] Embodiment 43

[0378] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, the sol-gel reaction in step S2 is not stirred. The rest of the contents are the same as those in embodiment 31.

[0379] Embodiment 44

[0380] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, the stirring speed of the sol-gel reaction in step S2 is 3100 rpm. The rest of the contents are the same as those in embodiment 31.

[0381] Embodiment 45

[0382] The difference between this embodiment and embodiment 31 is that in the preparation method provided in this embodiment, the solid content of the concentrated product in step S3 is 50 wt %. The rest of the contents are the same as those in embodiment 31.

[0383] Comparative Example 9

[0384] The difference between this comparative example and Example 31 is that in the preparation method provided in this comparative example, the addition of organic acid in step S1 is omitted. The rest of the contents are the same as those in Example 31.

[0385] Comparative Example 10

[0386] The difference between this comparative example and Example 31 is that in the preparation method provided in this comparative example, the addition of ammonium nitrate in step S2 is omitted. The rest of the contents are the same as those in Example 31.

[0387] Comparative Example 11

[0388] The difference between this comparative example and Example 31 is that in the preparation method provided in this comparative example, step S2 adjusts the pH of the second mixture to 4. The rest of the contents are the same as Example 31.

[0389] Comparative Example 12

[0390] The difference between this comparative example and Example 31 is that Pr(NO3)3 and Nd(NO3)3 are omitted in the preparation method provided in this comparative example. The rest of the contents are the same as those in Example 31.

[0391] The final products obtained from the above embodiments and comparative examples were tested to detect the particle size, crystallinity, and impurity content of the obtained products, and the particle size dispersion was calculated by the particle size of the particles. The calculation formula is: dispersion = (D90-D10) / D50. The impurity content in the obtained products was tested by inductively coupled plasma optical emission spectrometry (ICP-OES) to measure the content of the remaining elements in the products except cerium dioxide nanoparticles. The results are shown in Table 3.

[0392] Table 3

[0393] Particle size D50(nm) Particle size dispersion Impurity content (ppm) Crystallinity(%) Embodiment 31 190 2.15 <1 99 Embodiment 32 220 2.37 <1 99 Embodiment 33 280 1.67 <1 99 Embodiment 34 430 5.29 <10000 74 Embodiment 35 360 7.37 <1000 88 Embodiment 36 490 7.37 <1000 79 Embodiment 37 630 7.67 <1000 52 Embodiment 38 760 6.67 <1000 49 Embodiment 39 780 5.73 <1000 82 Embodiment 40 930 11.97 <1000 72 Embodiment 41 1070 10.33 <10000 84 Embodiment 42 300 4.97 <10000 76 Embodiment 43 1400 10.67 <100 54 Embodiment 44 220 5.77 <100 83 Embodiment 45 180 2.17 <100 92 Comparative Example 9 - - - - Comparative Example 10 230 7.67 <10 87 Comparative Example 11 235 5.13 <100 52 Comparative Example 12 195 6.87 <100 58

[0394] From Table 3 we can see that:

[0395] (1) It can be seen from Examples 31 to 33 that the preparation method adopted by the present invention introduces a doped metal salt into the cerium salt, which is then mixed with an inorganic acid and an organic acid. The obtained product is mixed with ammonia water and an ammonium salt under hydrothermal conditions, and the pH of the obtained mixture is subjected to a sol-gel reaction under strong acid conditions within a specific range to obtain a triangular cerium dioxide sol, which is then combined with a post-treatment process to obtain triangular cerium dioxide particles having a regular shape, good size uniformity, and high purity and crystallinity.

[0396] Figure 3 and Figure 4 The scanning electron microscope image of the triangular cerium dioxide prepared by the preparation process of Example 31 is given, and it can be seen from the figure that the nanoparticles present a flaky triangle and a triangular pyramid shape. The mass ratio of the triangular nano-flaky cerium dioxide obtained in Example 31 to the triangular pyramid-shaped tetrahedral cerium dioxide is about 4:1, wherein the average side length of the triangular nano-flaky cerium dioxide is 200nm, the average thickness is 8nm, and the average side length of the triangular pyramid-shaped cerium dioxide is 160nm.

[0397] (2) By comparing Example 31 with Examples 34-35, it can be seen that if the molar ratio of cerium ions in the cerium salt to the doped metal ions in the doped metal salt is too low, it will affect the formation of the final triangular cerium dioxide particles, resulting in uneven morphology and size of the triangular cerium dioxide and reduced polishing performance; if the molar ratio of the two is too high, it will affect the formation of the final triangular cerium dioxide particles, resulting in uneven morphology and size.

[0398] (3) By comparing Example 31 and Example 36, it can be seen that if the preparation process of the present invention is changed from adding the organic acid first and then the inorganic acid, and the inorganic acid and the organic acid are mixed at the same time, the morphology of the triangular cerium dioxide will be affected, resulting in a deterioration in the uniformity of the particle size.

[0399] (4) By comparing Example 31 with Examples 37-38, it can be seen that in the preparation process of triangular cerium dioxide of the present invention, regulating the volume ratio of inorganic acid to organic acid can control the reaction, avoid the relative volume of inorganic acid to organic acid being too low or too high affecting the morphology and particle uniformity of the prepared triangular cerium dioxide, and reduce the impurity content in cerium dioxide, thereby improving the crystallinity of the product.

[0400] (5) By comparing Example 31 with Examples 39-40, it can be seen that if the mixing speed in step S1 of the present invention is too low, the reaction progress in the preparation process of triangular cerium dioxide will be affected, thereby affecting the morphology and particle size uniformity of triangular cerium dioxide; if the mixing speed in step S1 is too high, a large number of microbubbles will be generated, which will reduce the particle size uniformity of the prepared triangular cerium dioxide particles.

[0401] (6) By comparing Example 31 with Examples 41-42, it can be seen that if the mass ratio of ammonia water to ammonium salt is too low, or the amount of ammonia water added is too little, the reaction will be incomplete, particles will agglomerate, the particle size of the obtained triangular particles will be larger, and the uniformity will deviate; if the mass ratio of ammonia water to ammonium salt is too high, or the amount of ammonium salt added is too little, a reaction that affects the preparation process of triangular cerium dioxide will occur, the uniformity of the particles will decrease, and the crystallinity of the product will be affected.

[0402] (7) By comparing Example 31 with Examples 43-44, it can be seen that if the stirring process in the sol-gel reaction process is omitted in the present invention, it will lead to uneven reaction, particle agglomeration, loss of control of morphology and size, and a decrease in crystallinity; if the stirring speed in the sol-gel reaction process is too high, a large number of microbubbles will be generated, affecting the performance of the final product.

[0403] (8) By comparing Example 31 and Example 45, it can be seen that if the solid content of the concentrated product of the present invention is too low, although it has little effect on the particle size, particle size dispersion, purity and crystallinity of the product, it will lead to a decrease in the content of the obtained triangular cerium dioxide and a decrease in the crystallinity of the final product.

[0404] (9) By comparing Example 31 with Comparative Example 9, it can be seen that if the addition of organic acid is omitted in the present invention, the internal reaction will not occur smoothly and a highly active intermediate cannot be obtained, thereby affecting the preparation of triangular cerium dioxide and even making it impossible to prepare cerium dioxide particles.

[0405] (10) By comparing Example 31 with Comparative Example 10, it can be seen that if the addition of ammonium salt is omitted in the present invention, the reaction in the preparation process of triangular cerium dioxide will be affected, so that the cerium dioxide product cannot be prepared.

[0406] (11) By comparing Example 31 and Comparative Example 11, it can be seen that if the pH of the present invention is adjusted too high, the morphology of cerium dioxide is affected, resulting in the generated cerium dioxide particles having an irregular morphology and being unable to be formed into a regular triangular morphology, thereby affecting the preparation content of triangular cerium dioxide, and further resulting in a decrease in the crystallinity of the particles.

[0407] (12) By comparing Example 31 and Comparative Example 12, it can be seen that if the doping of metal elements is omitted in the present invention, the morphology of the cerium dioxide particles will be affected, the hardness and crystallinity of the particles will deteriorate, and the polishing effect of the cerium dioxide particles will be affected.

[0408] In summary, the preparation method provided by the present invention is to mix cerium salt and doped metal salt with inorganic acid and organic acid in a solvent to obtain a composite cerium salt and a composite doped metal salt containing both inorganic acid radicals and organic acid radicals, and then under hydrothermal conditions, the composite cerium salt and the composite doped metal salt react with ammonia and ammonium salt to obtain a highly active intermediate, combined with the pH value in the reaction solution being precisely controlled to be within the range of 1-3, and the sol-gel reaction is carried out under a strong acidic condition of a specific pH, and the highly active intermediate can stably crystallize to form a specific shape of cerium dioxide seeds, and the seeds maintain a specific shape and continue to grow uniformly to form a triangular crystal nucleus with uniform size and regular morphology, and the crystal nucleus is gelled to obtain a triangular cerium dioxide sol with a triangular morphology, and the obtained sol is then subjected to a post-treatment process, and finally a large amount of triangular cerium dioxide particles with high purity and crystallinity are obtained. The present invention also introduces a specific praseodymium salt and / or neodymium salt as a doped metal salt in the cerium salt to promote the regulation of the product morphology and to improve the crystallinity of the product, thereby facilitating the polishing effect of the obtained material. The preparation method adopted by the present invention has short reaction time, simple operation and easy mass production. The prepared cerium dioxide has a triangular morphology with regular shape, uniform particles, good crystallinity and high purity, and can be widely used in semiconductor CMP polishing, high-end optical polishing or cosmetics and other fields.

[0409] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing spherical cerium dioxide, characterized in that: The preparation method comprises the following steps: (1) mixing a cerium salt, a doping metal salt, a solvent, an inorganic acid and an organic acid to obtain a first mixture; The doping metal salt includes praseodymium salt and / or neodymium salt; (2) under hydrothermal conditions, mixing the first mixture with ammonia water and ammonium salt to obtain a second mixture, wherein the pH value of the second mixture is 8-10, and performing a sol-gel reaction to obtain a spherical cerium dioxide sol; (3) Post-treating the quasi-spherical cerium dioxide sol to obtain the quasi-spherical cerium dioxide.

2. The preparation method according to claim 1, characterized in that: The ratio of the molar amount of cerium ions in the cerium salt in step (1) to the total molar amount of doped metal ions in the doped metal salt is (100-5000):1; Preferably, the doping metal salt in step (1) comprises praseodymium salt and neodymium salt; Preferably, when the doping metal salt comprises a praseodymium salt and a neodymium salt, the molar ratio of the praseodymium ions in the praseodymium salt to the neodymium ions in the neodymium salt is (1-10):1; Preferably, in step (1), the mass ratio of the cerium salt to the solvent is 1:(100-200); Preferably, the specific process of the first mixing in step (1) comprises: mixing the cerium salt, the doping metal salt, the solvent and the inorganic acid, and then adding the organic acid and continuing to mix to obtain the first mixture; Preferably, the volume ratio of the inorganic acid to the organic acid is (1.5-2.5):1; Preferably, the inorganic acid comprises nitric acid; Preferably, the organic acid comprises any one of formic acid, acetic acid, n-butyric acid, n-hexanoic acid or oxalic acid; Preferably, in step (1), the ratio of the total volume of the inorganic acid and the organic acid to the volume of the solvent is 3:(220-280); Preferably, the rotation speed of the first mixing in step (1) is 200-600 rpm; Preferably, the specific process of the second mixing in step (2) includes: under the hydrothermal conditions, the ammonia water and the ammonium salt are simultaneously mixed with the first mixture for a second time to obtain the second mixture; Preferably, the mass ratio of the ammonia water to the ammonium salt in step (2) is (3.5-4.5):2; Preferably, the concentration of the aqueous ammonia is 1-35wt%; Preferably, the temperature of the hydrothermal condition in step (2) is 30-100°C; Preferably, the pressure of the hydrothermal condition in step (2) is 0.1-20 MPa; Preferably, the temperature of the sol-gel reaction in step (2) is 50-160°C; Preferably, the sol-gel reaction in step (2) is also accompanied by stirring; Preferably, the stirring speed is 10-500 rpm; Preferably, the sol-gel reaction in step (2) is carried out until the solid content of the obtained spherical cerium dioxide sol is 0.1-40wt%; Preferably, the specific process of the post-treatment in step (3) comprises: concentrating the quasi-spherical cerium dioxide sol obtained in step (2), and then centrifuging, drying and deagglomerating to obtain the quasi-spherical cerium dioxide; Preferably, the concentration temperature is 120-180°C; Preferably, the concentration pressure is 0.1-100 MPa; Preferably, the concentration is performed until the solid content of the concentrated product is ≥ 60wt%; Preferably, the centrifugal speed is 500-5000 rpm; Preferably, the drying temperature is 300-1100°C; Preferably, the drying time is 2-12 hours.

3. A quasi-spherical cerium dioxide, characterized in that: The quasi-spherical cerium dioxide is prepared by the preparation method according to claim 1 or 2, and the quasi-spherical cerium dioxide includes doping elements, and the doping elements include praseodymium and / or neodymium; Preferably, the particle size D50 of the quasi-spherical cerium dioxide is 5-500 nm; Preferably, the specific surface area of ​​the spherical cerium dioxide is 20-250m 2 / g.

4. A use of the spherical cerium dioxide according to claim 3, characterized in that: The quasi-spherical cerium dioxide is applied to semiconductor chemical mechanical polishing, optical polishing or cosmetics.

5. A method for preparing hexagonal cerium dioxide, characterized in that: The preparation method comprises the following steps: (1) mixing a cerium salt, a doping metal salt, a solvent, an inorganic acid and an organic acid to obtain a first mixture; The doping metal salt includes praseodymium salt and / or neodymium salt; (2) under hydrothermal conditions, mixing the first mixture with ammonia water and ammonium salt to obtain a second mixture, wherein the pH value of the second mixture is 3.5-6, and performing a sol-gel reaction to obtain a hexagonal cerium dioxide sol; (3) Post-treating the hexagonal cerium dioxide sol to obtain the hexagonal cerium dioxide.

6. The preparation method according to claim 5, characterized in that: The ratio of the molar amount of cerium ions in the cerium salt in step (1) to the total molar amount of doped metal ions in the doped metal salt is (500-50000):1; Preferably, the doping metal salt in step (1) comprises praseodymium salt and neodymium salt; Preferably, when the doping metal salt comprises a praseodymium salt and a neodymium salt, the molar ratio of the praseodymium ions in the praseodymium salt to the neodymium ions in the neodymium salt is (1-10):1; Preferably, in step (1), the mass ratio of the cerium salt to the solvent is 1:(100-200); Preferably, the specific process of the first mixing in step (1) comprises: mixing the cerium salt, the doping metal salt, the solvent and the organic acid, and then adding the inorganic acid and continuing to mix to obtain the first mixture; Preferably, the volume ratio of the inorganic acid to the organic acid is (2.8-4):1; Preferably, the inorganic acid comprises nitric acid; Preferably, the organic acid comprises any one of formic acid, acetic acid, n-butyric acid, n-hexanoic acid or oxalic acid; Preferably, in step (1), the ratio of the total volume of the inorganic acid and the organic acid to the volume of the solvent is 3:(150-210); Preferably, the rotation speed of the first mixing in step (1) is 1000-15000 rpm; Preferably, the specific process of the second mixing in step (2) comprises: mixing the first mixture with the ammonium salt under the hydrothermal conditions, and then adding the ammonia water to the obtained mixed product to mix, so as to obtain the second mixture; Preferably, the mass ratio of the ammonia water to the ammonium salt is (4.8-6):2; Preferably, the concentration of the aqueous ammonia is 1-35wt%; Preferably, the temperature of the hydrothermal condition in step (2) is 30-100°C; Preferably, the pressure of the hydrothermal condition in step (2) is 0.1-20 MPa; Preferably, the temperature of the sol-gel reaction in step (2) is 50-160°C; Preferably, the sol-gel reaction in step (2) is also accompanied by stirring; Preferably, the stirring speed is 200-2000rpm; Preferably, the sol-gel reaction in step (2) is carried out until the solid content of the obtained hexagonal cerium dioxide sol is 0.1-40wt%; Preferably, the specific process of the post-treatment in step (3) includes: concentrating the hexagonal cerium dioxide sol obtained in step (2), and then centrifuging, drying and deagglomerating to obtain the hexagonal cerium dioxide; Preferably, the concentration temperature is 120-180°C; Preferably, the concentration pressure is 0.1-100 MPa; Preferably, the concentration is performed until the solid content of the concentrated product is ≥ 60wt%; Preferably, the centrifugal speed is above 2000 rpm; Preferably, the drying temperature is 300-1100°C; Preferably, the drying time is 2-12 hours.

7. A hexagonal cerium dioxide, characterized in that: The hexagonal cerium dioxide is prepared by the preparation method according to claim 5 or 6, and the hexagonal cerium dioxide includes doping elements, and the doping elements include praseodymium and / or neodymium; Preferably, the particle size D50 of the hexagonal cerium dioxide is 5-500 nm; Preferably, the side length of the hexagonal cerium dioxide is 60-160nm; Preferably, the thickness of the hexagonal cerium dioxide is 2-20 nm; Preferably, the specific surface area of ​​the hexagonal cerium dioxide is 100-250m 2 / g.

8. A use of hexagonal cerium dioxide according to claim 7, characterized in that: The hexagonal cerium dioxide is applied to semiconductor chemical mechanical polishing, optical polishing or cosmetics.

9. A method for preparing triangular cerium dioxide, characterized in that: The preparation method comprises the following steps: (1) mixing a cerium salt, a doping metal salt, a solvent, an inorganic acid and an organic acid to obtain a first mixture; The doping metal salt includes praseodymium salt and / or neodymium salt; (2) under hydrothermal conditions, mixing the first mixture with ammonia water and ammonium salt to obtain a second mixture, wherein the pH value of the second mixture is 1-3, and performing a sol-gel reaction to obtain a triangular cerium dioxide sol; (3) Post-treating the triangular cerium dioxide sol to obtain the triangular cerium dioxide.

10. The preparation method according to claim 9, characterized in that: The ratio of the molar amount of cerium ions in the cerium salt in step (1) to the total molar amount of doped metal ions in the doped metal salt is (1000-500000):1; Preferably, the doping metal salt in step (1) comprises praseodymium salt and neodymium salt; Preferably, when the doping metal salt comprises a praseodymium salt and a neodymium salt, the molar ratio of the praseodymium ions in the praseodymium salt to the neodymium ions in the neodymium salt is (1-10):1; Preferably, in step (1), the mass ratio of the cerium salt to the solvent is 1:(100-200); Preferably, the specific process of the first mixing in step (1) comprises: mixing the cerium salt, the doping metal salt, the solvent and the organic acid, and then adding the inorganic acid and continuing to mix to obtain the first mixture; Preferably, the volume ratio of the inorganic acid to the organic acid is (6-10):3; Preferably, the inorganic acid comprises nitric acid; Preferably, the organic acid comprises any one of formic acid, acetic acid, n-butyric acid, n-hexanoic acid or oxalic acid; Preferably, in step (1), the ratio of the total volume of the inorganic acid and the organic acid to the volume of the solvent is 3:(80-140); Preferably, the rotation speed of the first mixing in step (1) is 1000-2000 rpm; Preferably, the specific process of the second mixing in step (2) includes: mixing the first mixture with the ammonia water under the hydrothermal conditions, and then adding the ammonium salt to the obtained mixed product to obtain the second mixture; Preferably, the mass ratio of the ammonia water to the ammonium salt is (8-12):2; Preferably, the concentration of the aqueous ammonia is 1-35wt%; Preferably, the temperature of the hydrothermal condition in step (2) is 30-100°C; Preferably, the pressure of the hydrothermal condition in step (2) is 0.1-20 MPa; Preferably, the temperature of the sol-gel reaction in step (2) is 50-160°C; Preferably, the sol-gel reaction in step (2) is also accompanied by stirring; Preferably, the stirring speed is 300-3000rpm; Preferably, the sol-gel reaction in step (2) is carried out until the solid content of the obtained triangular cerium dioxide sol is 0.1-40wt%; Preferably, the specific process of the post-treatment in step (3) comprises: concentrating the triangular cerium dioxide sol obtained in step (2), and then centrifuging, drying and deagglomerating to obtain the triangular cerium dioxide; Preferably, the concentration temperature is 120-180°C; Preferably, the concentration pressure is 0.1-100 MPa; Preferably, the concentration is performed until the solid content of the concentrated product is ≥ 60wt%; Preferably, the centrifugal speed is 2000-6000rpm; Preferably, the drying temperature is 300-1100°C; Preferably, the drying time is 2-12 hours.

11. A triangular cerium dioxide, characterized in that: The triangular cerium dioxide is prepared by the preparation method according to claim 9 or 10, and the triangular cerium dioxide includes doping elements, and the doping elements include praseodymium and / or neodymium; Preferably, the particle size D50 of the triangular cerium dioxide is 5-500 nm; Preferably, the triangular cerium dioxide comprises triangular nano-sheet cerium dioxide and / or triangular pyramid cerium dioxide; Preferably, the triangular cerium dioxide includes triangular nano-sheet cerium dioxide and triangular pyramid cerium dioxide; Preferably, the mass ratio of the triangular nano-sheet cerium dioxide to the triangular pyramid cerium dioxide is 2:(0.1-1); Preferably, the triangular nanosheet cerium dioxide has a side length of 80-300 nm and a thickness of 2-20 nm; Preferably, the side length of the triangular pyramid-shaped cerium dioxide is 50-180 nm; Preferably, the specific surface area of ​​the triangular cerium dioxide is 10-200m 2 / g.

12. A use of the triangular cerium dioxide according to claim 11, characterized in that: The triangular cerium dioxide is applied to semiconductor chemical mechanical polishing, optical polishing or cosmetics.

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